一。比较结构的原则：
A. 逻辑意思表达清晰，结构完整。逻辑意思完整的重点是要保证比较结构的合理，从而不会产生任何歧义。
关于比较的结构，大N cwang 有非常精辟的贴子：http://forum.chasedream.com/dispbbs.asp?boardid=23&id=103101
常见的比较的结构有： 主语比较；宾语比较；介宾比较；状语比较；
其中又根据句子的结构分成：主谓宾全的句子比较；主系表的句子比较;主谓+介宾/状语/其他修饰结构的句子比较
B. 比较对象对等。这里面包括含义，数，在句子里成分上的对等。
C. 简洁原则。在保证逻辑意思表达清晰和比较对象对等的情况下，比较结构也继承GMAT一贯的尽量简洁的原则，省略掉比较前后完全相同的成分。但是简洁的前提是不能造成比较对象上的歧义。
从做题的重要性来说，上面的原则中 A > B > C.
二。比较结构的分类：
1. more...than 结构
2. as + adj. + as 结构
3. as + 从句 or like/unlike +n. ，比较对象 的结构
4. 其他，如rather than, instead of, etc....
三。常见错误的分类
依据上述的比较结构的原则，相应GMAT中比较结构出现的错误有以下几种：
#1.比较的结构错误：例如将主语比较改变成宾语比较；介宾比较改变成主语比较，等。。
#2.比较的对象错误：比较对象的含义，数，在句子里成分上的不对等。
#3.比较词的错误：包括 More..than / as...as 的搭配错误，比较的形容词/副词和所修饰词的搭配错误，如 greater/more..than.
根据二和三中的分类，将OG10SC中涉及到比较的题目一一分类总结。
为了方便大家阅读，我把下面楼的主干内容总结一下，没有时间和兴趣看具体的OG题目的XDJM们只用看这些就好了：
比较词的错误：
比较词的错误分三种情况：
1.构成比较的连词搭配错误或不完整：即as...as ; more... than 的搭配
通常出现的错误形式有 as...than ; more....as；more... rather than 等
不完整的情况有 as many 后面缺少as/ more后面缺少than 等
2.构成比较的形容词/副词和修饰对象的搭配错误。包括修饰的形容词/副词的搭配等。
如OG 中出现的 the number ...greater than / more than 的错误
3.比较结构的冗余。
如 as many as , more than , 同时出现的结构。
二。比较结构和比较对象的错误。
这两种错误通常会交织在一起，因此我就按照上边比较结构的分类来分别总结：
1. more...than 结构
按照原则A中出现的大N cwang 贴子：http://forum.chasedream.com/dispbbs.asp?boardid=23&id=103101
常见的比较的结构有： 主语比较；宾语比较；介宾比较；状语比较；
其中又根据句子的结构分成：主谓宾全的句子比较；主系表的句子比较;主谓+介宾/状语/其他修饰结构的句子比较
A.主语比较 ==》这个是变化最多的一种，通常的分歧在于主语比较的时候的动词是否需要补出。
其实总体的原则非常的简单：
#1 对于主谓宾全或者主谓+介宾短语的句子的主语比较，谓语动词必须补出，其主要目地是为了和宾语比较区分开来，防止歧义。
#2 对于主系表或者主谓+其他非名词性结构修饰成分的句子的主语比较，由于谓语动词之后不存在名词性结构造成歧义，谓语动词省略。
B.宾语比较 ==》这种比较之存在于主谓宾全的句子中。需要和主谓宾全的句子的主语比较 以及 介宾结构的比较区分。
另外一点需要注意的是这种比较的宾语通常用代词+介词+对应的主语比较对象组成，需要和主谓宾全的句子的主语比较区分。
C.介宾短语的比较 ==》这种比较需要和宾语比较进行区分，一定要补出介词。其原因是介宾短语中的宾语和整句的宾语在句中成分不同，需要强调出是那些在比较，消除歧义。另一个是这个介宾短语不能是句子主语的修饰成分比较，如果是，则需要变换成主语比较形式。（下面的OG200 E选项）
D.状语的比较 ==》这种比较可以分成时间状语比较，原因状语比较等。常见的是时间状语比较，而且通常会有很多的省略, 用 than ever before/ any pervious 等表示缺省的和当前的比较。
E.特殊结构的比较 ==》这种比较类似于固定用法，有 than expected / than usual 等。
例外：
OG46：主语比较_主谓宾句型
此题目是主谓宾全的主语比较结构，应该需要补出谓语动词。但是由于比较结构中的并列谓语require and gain 的出现，如果补出do 会造成不知道指向那里的歧义出现，为了表达清楚，所以省略了谓语动词。
2. as...as 结构
as...as 结构总体上分两种： as + adj. +as ; the same as...
其比较的主要的原则和more..than的结构是一样的,但是变化更多，GMAT更喜欢考。
A.主语比较 ==》比较原则是一样的，但是需要注意的是有一种特殊情况下，as adj. as 结构中的第二个as 会做代词做後一个比较结构的主语，从而从结构上看起来是只有宾语和谓语的比较。
#1 对于主谓宾全或者主谓+介宾短语的句子的主语比较，谓语动词必须补出，其主要目地是为了和宾语比较区分开来，防止歧义。as+adj.+as 的比较结构的主语比较更复杂，有时候会把宾语放在as..as 之间，形成as +adj.+宾语+as 的结构，这种形式上看起来是只有主谓句的比较，实质上是主谓宾全的句子，需要补出谓语。
但是当A do as +adj.+宾语+as B do 变成 A do as +adj.+ as+ B +不定式, 谓语动词省略. GWD/Prep有这种类型的题目。
#2 对于主系表或者主谓+其他非名词性结构修饰成分的句子的主语比较，由于谓语动词之后不存在名词性结构造成歧义，谓语动词省略。
#3 as...as 结构中有一种特殊结构是在第二个as 做代词的情况下，此时比较的前后都是完整的句子。
B.宾语比较 ==》这种比较之存在于主谓宾全的句子中。需要和主谓宾全的句子的主语比较 以及 介宾结构的比较区分。
另外一点需要注意的是这种比较的宾语通常用代词+介词+对应的主语比较对象组成，需要和主谓宾全的句子的主语比较区分。
特殊：the same as：the same as 也符合比较结构的大的原则：
3. Like+n. 与 as+句子的比较结构
关于Like+n. 和 as+句子的这种比较结构，也是ＧＭＡＴ perfer 的考点之一。其重点就是快速判断除like / as 对应的比较对象是否合理，从而排除选项。
like / as的差别就在于Like 后面只能接名词性结构，而 as 后面的必须是完整的句子或者不引起歧义下的省略成分，但是不能是简单的名词性结构。当Like和as都同时可以使用的时候， like+n.是更加简洁的结构，因此GMAT更加perfer.
一。like+n. 比较结构
like+n. 的比较通常放在句首，其比较对象是句子的主语。因此看到这类型的题目首先判断的就是对应的主语是否和like后面接的名词是对等的对象。
但是，需要注意的是，like+n.结构也能放在句中或这句末，在OG和PrepSC中都有这样的题目。其原则就是不能有歧义出现。
关于这一点，有大N的帖子：http://forum.chasedream.com/dispbbs.asp?BoardID=23&ID=48608
二 as+句子 比较结构
as + 句子的比较结构和like+n.的用法类似，但是as 后面不能接简单的名词性结构。
4. 其他，如rather than, instead of, etc....
除1-3中的比较结构之外，还有一些结构或者比较词引导的特殊类型的比较结构。这些比较结构在GMAT中出现相对较少，但是同样需要掌握。
5. 与比较有关或者容易混淆的结构。
在ＧＭＡＴ中还有一些结构是和比较有关的，而且和通常的比较结构容易混淆。
尤其是在as 的使用上，由于有很多as组成的固定搭配和as做其他成分的使用方法，复习时需要注意和比较的结构区分开。
先从最简单的错误开始：比较词的错误
比较词的错误分三种情况：
1.构成比较的连词搭配错误或不完整：即as...as ; more... than 的搭配
通常出现的错误形式有 as...than ; more....as；more... rather than 等
不完整的情况有 as many 后面缺少as/ more后面缺少than 等
例：OG116 的 better than / instead of/rather than 的选择
116. Those who come to church with a predisposition to religious belief will be happy in an auditorium or even a storefront, and there is no doubt that religion is sometimes better served by adapted spaces of this kind instead of by some of the buildings actually designed for it.
(A) adapted spaces of this kind instead of by some of the buildings actually designed for it
(B) adapted spaces like these rather than some of the buildings actually designed for them
(C) these adapted spaces instead of by some of the buildings actually designed for it
(D) such adapted spaces rather than by some of the buildings actually designed for them
(E) such adapted spaces than by some of the buildings actually designed for it
Choice E, the best answer, correctly uses the construction is better served by x than by y and supplies the proper singular pronoun, it, to refer to religion. Choices A and B complete the construction beginning better served by x... unidiomatically, with instead of by y and rather than y. Also in B, them does not agree with its logical referent, religion. Choice C repeats the unidiomatic instead construction; in addition, such is preferable to these for presenting examples or instances. Choice D repeats the errors with rather than and them.
例：OG5 的 older than / as old as 的选择
OG5. Carbon-14 dating reveals that the megalithic monuments in Brittany are nearly 2,000 years as old as any of their supposed Mediterranean predecessors.
(A) as old as any of their supposed
(B) older than any of their supposed
(C) as old as their supposed
(D) older than any of their supposedly
(E) as old as their supposedly
Choices A, C, and E do not state the comparison logically. The expression as old as indicates equality of age, but the sentence indicates that the Brittany monuments predate the Mediterranean monuments by 2,000 years. In B, the best choice, older than makes this point of comparison clear. B also correctly uses the adjective supposed, rather than the adverb supposedly used in D and E, to modify the noun phrase Mediterranean predecessors.
2.构成比较的形容词/副词和修饰对象的搭配错误。包括修饰的形容词/副词的搭配等。
如OG 中出现的 the number ...greater than / more than 的错误
例：OG46 的 quick/quickly 和 gain /require 的搭配。
OG46. A study commissioned by the Department of Agriculture showed that if calves exercise and associated with other calves, they will require less medication and gain weight quicker than do those raised in confinement.
(A) associated with other calves, they will require less medication and gain weight quicker than do
(B) associated with other calves, they require less medication and gain weight quicker than
(C) associate with other calves, they required less medication and will gain weight quicker than do
(D) associate with other calves, they have required less medication and will gain weight more quickly than do
(E) associate with other calves, they require less medication and gain weight more quickly than
Choice E, the best answer, uses the adverbial phrase more quickly than to modify the verb phrase gain weight. In A, B, and C, quicker than is incorrect because an adjective should not be used to modify a verb phrase. E is also the only choice with consistent verb tenses. The first verb in the clauses introduced by showed that is exercise. A and B incorrectly compound that present tense verb with a past tense verb, associated. C and D correctly use associate, but C follows with the past tense required and D with the present perfect have required. Both C and D incorrectly conclude with the future tense will gain.
例：OG161 的 more numerous than/ greater than 和 the density of the timber wolf population 的搭配。
161. A wildlife expert predicts that the reintroduction of the caribou into northern Minnesota would tail if the density of the timber wolf population in that region is more numerous than one wolf for every 39 square miles.
(A) would fail if the density of the timber wolf population in that region is more numerous than
(B) would fail provided the density of the timber wolf population in that region is more than
(C) should fail if the timber wolf density in that region was greater than
(D) will fail if the density of the timber wolf population in that region is greater than
(E) will fail if the timber wolf density in that region were more numerous than
D, the best choice, uses a correct sequence of present and future indicative verb forms--predicts, will fail, and is--in the three related clauses. Density, an abstract "mass" noun, is logically construed with greater than. In A and B, would fail disagrees with the other verbs in tense and mood. Choice A misconstrues density with more numerous than, and B uses the pretentious and illogical word provided for ifm a conditional clause after a negative idea (would fail). C's should fail and was are confusing and inconsistent with predicts. C and E use the absurd phrase timber wolf density. (The wolves are not dense; their population is dense.) E also uses an inconsistent subjunctive form, were, and misconstrues density with more numerous than.
3.比较结构的冗余。
如 as many as , more than , 同时出现的结构。
例：OG266 的 at least as strong a Clean Air Act as / as strong or stronger than
266. In a recent poll, 86 percent of the public favored a Clean Air Act as strong or stronger than the present act.
(A) a Clean Air Act as strong or stronger than
(B) a Clean Air Act that is stronger, or at least so strong as,
(C) at least as strong a Clean Air Act as is
(D) a Clean Air Act as strong or stronger than is
(E) a Clean Air Act at least as strong as
E, the best choice, is concise, clear, and idiomatic. Choices A, B, C, and D may be faulted for constructions that are cumber?some, unnecessarily wordy, or unidiomatic. Choices A and D require as strong as instead of as strong. Similarly, B is missing than after stronger, and so should be as. In C and D, is should be dropped. Even with revisions, these choices are more wordy and awkward than the best answer.
二。比较结构和比较对象的错误。
这两种错误通常会交织在一起，因此我就按照上边比较结构的分类来分别总结：
1. more...than 结构
按照原则A中出现的大N cwang 贴子：http://forum.chasedream.com/dispbbs.asp?boardid=23&id=103101
常见的比较的结构有： 主语比较；宾语比较；介宾比较；状语比较；
其中又根据句子的结构分成：主谓宾全的句子比较；主系表的句子比较;主谓+介宾/状语/其他修饰结构的句子比较
A.主语比较 ==》这个是变化最多的一种，通常的分歧在于主语比较的时候的动词是否需要补出。
其实总体的原则非常的简单：
#1 对于主谓宾全或者主谓+介宾短语的句子的主语比较，谓语动词必须补出，其主要目地是为了和宾语比较区分开来，防止歧义。
例 OG133： 主语比较_主谓宾句型
Holland spends a larger + 宾语 + than the United States does ； 补出does,防止了产生 the United States 和 its gross national product 比较的歧义。133. In Holland, a larger percentage of the gross national product is spent on defense of their coasts from rising seas than is spent on military defense in the United States.
(A) In Holland, a larger percentage of the gross national product is spent on defense of their coasts from rising seas than is spent on military defense in the United States.（比较结构错误）
(B) In Holland they spend a larger percentage of their gross national product on defending their coasts from rising seas than the United States does on military defense.（比较结构不完整，比较对象错误）
(C) A larger percentage of Holland's gross national product is spent on defending their coasts from rising seas than the United States spends on military defense. （比较结构完整，比较对象错误）
(D) Holland spends a larger percentage of its gross national product defending its coasts from rising seas than the military defense spending of the United States.（比较结构不完整，比较对象错误）
(E) Holland spends a larger percentage of its gross national product on defending its coasts from rising seas than the United States does on military defense.（比较结构完整，比较对象正确）
In choices A, B, and C, the plural pronouns their and they have no plural noun for a logical referent. Since In Holland modifies all of the sentence that follows, A states confusedly that Holland spends a percentage of its gross national product on military defense in the United States. In C, the passive is spent is not parallel with the active spends. Lack of parallelism in choice D produces an illogical comparison: the percentage that Holland spends is said to exceed not the percentage that the United States spends but rather its total military defense spending. Parallel phrasing allows E, the best choice, to make a logical comparison between what Holland spends and what the United States does [spend].
例 OG199： 主语比较_主谓宾句型 an earthquake... will typically devastate an area 和 will a quake。。。的比较
199. Because the Earth's crust is more solid there and thus better able to transmit shock waves, an earthquake of a given magnitude typically devastates an area 100 times greater in the eastern United States than it does in the West.
(A) of a given magnitude typically devastates an area 100 times greater in the eastern United States than it does in the West （比较结构完整，比较对象错误）
(B) of a given magnitude will typically devastate 100 times the area if it occurs in the eastern United States instead of the West（比较结构不完整，比较对象错误，比较词错误）
(C) will typically devastate 100 times the area in the eastern United States than one of comparable magnitude occurring in the West（比较结构不完整）
(D) in the eastern United States will typically devastate an area 100 times greater than will a quake of comparable magnitude occurring in the West（比较结构完整，比较对象正确）
(E) that occurs in the eastern United States will typically devastate 100 times more area than if it occurred with comparable magnitude in the West（比较结构不完整，比较对象错误）
At issue is the accurate expression of a complex comparison. Choice D, the best answer, presents the proper form of comparison, will typically devastate an area 100 times greater than will; thus, choice D logically indicates that earthquakes in the eastern United States are 100 times more devastating than are western earthquakes. Choices A, B, and E use it incorrectly to suggest that the same quake strikes both the eastern and the western United States. In choice C, 700 times the area... than is unidiomatic.
例 OG224： 主语比较_主谓+介宾句型
Inuits of the Bering Sea 和 Aleuts or Inuits of the North Pacific and northern Alaska 比较；补出were，防止Aleuts or Inuits of the North Pacific and northern Alaska.和介宾结构中的contact with Europeans 比较。
224. Inuits of the Bering Sea were in isolation from contact with Europeans longer than Aleuts or Inuits of the North Pacific and northern Alaska.
(A) in isolation from contact with Europeans longer than
(B) isolated from contact with Europeans longer than
(C) in isolation from contact with Europeans longer than were
(D) isolated from contact with Europeans longer than were
(E) in isolation and without contacts with Europeans longer than
The phrasing of the comparisons in choices A, B, and E is incomplete, so the comparisons are ambiguous: because longer than could be followed by either from or were, it is unclear whether Inuits of the Bering Sea were isolated from Europeans longer than from the other Native American groups, or whether they were isolated from Europeans longer than the other groups were. In A and C, in isolation from contact is wordy and unidiomatic. The awkward phrasing of E further distorts the sense of the sentence: because with cannot idiomatically serve as the preposition for in isolation, the sentence suggests that the Bering Sea Inuits were totally isolated. Choice D is best: it employs concise, idiomatc phrasing to express a logically complete comparison.
#2 对于主系表或者主谓+其他非名词性结构修饰成分的句子的主语比较，由于谓语动词之后不存在名词性结构造成歧义，谓语动词省略。
OG118: 主语比较_主系表句型 their economic bases 和 those of most predominantly White colleges 比较
1l8. The question of whether to divest themselves of stock in companies that do business in South Africa is particularly troublesome for the nation's 116 private Black colleges because their economic bases are often more fragile than most predominantly White colleges.
(A) than
(B) than those of
(C) than is so of
(D) compared to
(E) compared to those of
Choice B, the best answer, correctly uses the construction more fragile ... than to compare the economic bases of private Black colleges with those of most predominantly White colleges. Choice A fails to supply a phrase like those of, thus illogically comparing the Black colleges' economic bases to predominantly White colleges. Similarly, in C than is so of does not clearly identify the second term of the comparison and is unnecessarily wordy. Like A, D makes an illogical comparison between bases and colleges, and both D and E use the unidiomatic and redundant more ... compared to.
OG137:主语比较_主系表句型
137. In 1982 the median income for married-couple families with a wage-earning wife was $9,000 more than a family where the husband only was employed.
(A) a family where the husband only
(B) of a family where only the husband
(C) that for families in which only the husband
(D) a family in which only the husband
(E) those of families in which the husband only
Choices A and D illogically compare the median income to a family rather than to another median income. Also, families would be preferable to a family in A, B, and D because the comparison is between groups of families. In A and B, in which would be preferable to where, since where properly refers to location. Choices A and E misplace only so that it seems to modify was employed rather than the husband. In B and E, of is less idiomatic than for, and the plural pronoun those in E does not agree with the singular noun referent income. C, the best choice, uses the singular pronoun that to stand for income, thus establishing a logical comparison.
OG161：主语比较_主系表句型
161. A wildlife expert predicts that the reintroduction of the caribou into northern Minnesota would tail if the density of the timber wolf population in that region is more numerous than one wolf for every 39 square miles.
(A) would fail if the density of the timber wolf population in that region is more numerous than
(B) would fail provided the density of the timber wolf population in that region is more than
(C) should fail if the timber wolf density in that region was greater than
(D) will fail if the density of the timber wolf population in that region is greater than
(E) will fail if the timber wolf density in that region were more numerous than
D, the best choice, uses a correct sequence of present and future indicative verb forms--predicts, will fail, and is--in the three related clauses. Density, an abstract "mass" noun, is logically construed with greater than. In A and B, would fail disagrees with the other verbs in tense and mood. Choice A misconstrues density with more numerous than, and B uses the pretentious and illogical word provided for ifm a conditional clause after a negative idea (would fail). C's should fail and was are confusing and inconsistent with predicts. C and E use the absurd phrase timber wolf density. (The wolves are not dense; their population is dense.) E also uses an inconsistent subjunctive form, were, and misconstrues density with more numerous than.
B.宾语比较 ==》这种比较之存在于主谓宾全的句子中。需要和主谓宾全的句子的主语比较 以及 介宾结构的比较区分。
另外一点需要注意的是这种比较的宾语通常用代词+介词+对应的主语比较对象组成，需要和主谓宾全的句子的主语比较区分。
OG19：宾语比较_主谓宾句型 protein of higher quality 和 that in wheat 比较。通过用 that 指代protein ，形成 protein in wheat 和 前面的protein比较，非常有迷惑性。
19. In addition to having more protein -than wheat does, the protein in rice is higher quality than that in wheat, with more of the amino acids essential to the human diet.
(A) the protein in rice is higher quality than that in
(B) rice has protein of higher quality than that in
(C) the protein in rice is higher in quality than it is in
(D) rice protein is higher in quality than it is in
(E) rice has a protein higher in quality than
In this sentence, the initial clause modifies the nearest noun, identifying it as the thing being compared with wheat. By making protein the noun modified, choices A, C, and D illogically compare wheat with protein and claim that the protein in rice has more protein than wheat does. In C and D, the comparative structure higher in quality than it is in wheat absurdly suggests that rice protein contains wheat. B, the best choice, logically compares wheat to rice by placing the noun rice immediately after the initial clause. B also uses that to refer to protein in making the comparison between the proteins of rice and wheat. Choice E needs either that in or does after wheat to make a complete and logical comparison.
OG112：宾语比较_不定式宾语
112. Domestic automobile manufacturers have invested millions of dollars into research to develop cars more gasoline-efficient even than presently on the road.
(A) into research to develop cars more gasoline-efficient even than presently on the road
(B) into research for developing even more gasoline-efficient cars on the road than at present
(C) for research for cars to be developed that are more gasoline-efficient even than presently the road
(D) in research to develop cars even more gasoline-efficient than those at present on the road
(E) in research for developing cars that are even more gasoline-efficient than presently on the road
Choice D, the best answer, uses the preposition than to compare two clearly specified and grammatically parallel terms, the cars the manufacturers hope to develop and those at present on the road. In A, the phrase more gasoline-efficient ... than presently on the road does not identify the second term of the comparison. In B, the misuse of modifying phrases produces an ambiguous and awkward statement: even more gasoline-efficient cars could refer either to more cars that are efficient or to cars that are more efficient. Choices B, C, and E all use research for [verb] where the idiom requires research to [verb]. In addition, C awkwardly separates even from more, and C and E again fail to indicate the second term of the comparison.
C.介宾短语的比较 ==》这种比较需要和宾语比较进行区分，一定要补出介词。其原因是介宾短语中的宾语和整句的宾语在句中成分不同，需要强调出是那些在比较，消除歧义。另一个是这个介宾短语不能是句子主语的修饰成分比较，如果是，则需要变换成主语比较形式。（下面的OG200 E选项）
OG116：介宾短语比较_主谓宾+介宾短语
116. Those who come to church with a predisposition to religious belief will be happy in an auditorium or even a storefront, and there is no doubt that religion is sometimes better served by adapted spaces of this kind instead of by some of the buildings actually designed for it.
(A) adapted spaces of this kind instead of by some of the buildings actually designed for it
(B) adapted spaces like these rather than some of the buildings actually designed for them
(C) these adapted spaces instead of by some of the buildings actually designed for it
(D) such adapted spaces rather than by some of the buildings actually designed for them
(E) such adapted spaces than by some of the buildings actually designed for it
Choice E, the best answer, correctly uses the construction is better served by x than by y and supplies the proper singular pronoun, it, to refer to religion. Choices A and B complete the construction beginning better served by x... unidiomatically, with instead of by y and rather than y. Also in B, them does not agree with its logical referent, religion. Choice C repeats the unidiomatic instead construction; in addition, such is preferable to these for presenting examples or instances. Choice D repeats the errors with rather than and them.
OG200. 介宾短语比较_主谓宾+介宾短语
200. Certain pesticides can become ineffective if used repeatedly in the same place: one reason is suggested by the finding that there are much larger populations of pesticide-degrading microbes in soils with a relatively long history of pesticide use than in soils that are free of such chemicals.
(A) Certain pesticides can become ineffective if used repeatedly in the same place; one reason is suggested by the finding that there are much larger populations of pesticide-degrading microbes in soils with a relatively long history of pesticide use than in soils that are free of such chemicals.
(B) If used repeatedly in the same place, one reason that certain pesticides can become ineffective is suggested by the finding that there are much larger populations of pesticide-degrading microbes in soils with a relatively long history of pesticide use than in soils that are free of such chemicals.
(C) If used repeatedly in the same place, one reason certain pesticides can become ineffective is suggested by the finding that much larger populations of pesticide-degrading microbes are found in soils with a relatively long history of pesticide use than those that are free of such chemicals.
(D) The finding that there are much larger populations of pesticide-degrading microbes in soils with a relatively long history of pesticide use than in soils that are free of such chemicals is suggestive of one reason, if used repeatedly in the same place, certain pesticides can become ineffective.
(E) The finding of much larger populations of pesticide-degrading microbes in soils with a relatively long history of pesticide use than in those that are free of such chemicals suggests one reason certain pesticides can become ineffective if used repeatedly in the same place. （主语+介宾短语+谓语+比较词+介宾短语错误)
Choice A, the best answer, is the only one that manages syntactic control of the sentence. The sentence consists of two independent clauses, beginning Certain pesticides ... and one reason, which are connected by a semicolon. Dangling or misplaced modifiers plague choices B, C, and D: in each case, the phrase if used repeatedly in the same place illogically modifies one reason rather than certain pesticides. In choice E, The finding of much larger populations .. . than in those that is an improperly constructed comparison.
介宾短语比较_主系表+介宾短语
254. Balding is much more common among White males than males of other races.
(A) than
(B) than among
(C) than is so of
(D) compared to
(E) in comparison with
B, the best choice, correctly uses the idiomatic construction more common among x than among y. In A, the comparison is not parallel and not clear; one illogical but available reading is that balding is more common among White males than are males of other races. To be clear, the sentence should read more common among White males than among .... In C, the phrase is so cannot refer to the process Balding, and more common among ... than is so lacks parallelism. In D and E, the phrases more common... compared to and more common ... in comparison with are redundant and unidiomatic. The correct form is more common than.
D.状语的比较 ==》这种比较可以分成时间状语比较，原因状语比较等。常见的是时间状语比较，而且通常会有很多的省略, 用 than ever before/ any pervious 等表示缺省的和当前的比较。
OG98:时间状语比较_主谓状+全省略： than ever before
98. The financial crash of October 1987 demonstrated that the world's capital markets are integrated more closely than never before and events in one part of the global village may be transmitted to the rest of the village--almost instantaneously.
(A) integrated more closely than never before and
(B) closely integrated more than ever before so
(C) more closely integrated as never before while
(D) more closely integrated than ever before and that
(E) more than ever before closely integrated as
Choice D, the best answer, produces a clear sentence in which parallel structure (two clauses introduced by that) underscores meaning: the crash demonstrated [1] that markets are integrated and [2] that events may be transmitted. The other choices lack this parallel structure and contain additional faults. The phrases more... than never in A and more ... as never in C are both unidiomatic: the idiom is more than ever. Choices B, C, and E end with so, while, and as, respectively:and that is needed so that two parallel clauses may be properly joined. Finally, B and E misplace the adverb more, which here should come just before closely: closer, not more frequent, integration of the world's capital markets is what facilitates the transmission of economic events.
OG251: 时间状语比较_主系表+状 now 和 when时间状语从句的比较
251. The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than when the use of DDT was sharply restricted in the early 1970's. .
(A) extinction; its numbers are now five times greater than
(B) extinction; its numbers are now five times more than
(C) extinction, their numbers now fivefold what they were
(D) extinction, now with fivefold the numbers they had
(E) extinction, now with numbers five times greater than
A, the best choice, uses a singular pronoun, its, to refer to the singular antecedent The gyrfalcon, and it properly uses the construction its numbers are now ... greater than. In B, the construction its numbers are ... more is not idiomatic: there are more birds, but not more numbers. Choices C and D use a plural pronoun, their or they, to refer to a grammatically singular antecedent, The gyrfalcon. Choices D and E wrongly use a phrase introduced by now with to modify The gyrfalcon. In both choices, the phrase confusingly seems to parallel with extinction; a new clause with a present tense verb is needed to state what the gyrfalcon's numbers are now.
OG198: 时间状语比较_主谓宾+介宾+状+全省略：此题从形式上是介宾短语的比较省略形式，但是表示的是先后时间上的比较，故归类于此。
198. Although Napoleon's army entered Russia with far more supplies than they had in their previous campaigns, it had provisions for only twenty-four days.
(A) they had in their previous campaigns
(B) their previous campaigns had had
(C) they had for any previous campaign
(D) in their previous campaigns
(E) for any previous campaign
If than is followed by a clause referring to army, the subject of that clause must be singular (it). Furthermore, the verb of that clause will need to be in the past perfect form (had had) because it refers to a time before the simple past of entered. Finally, the preposition/or is more precise than in because supplies are gathered/or an upcoming campaign. Choices A and C incorrectly use the plural they and the simple past had. Moreover, A uses the less precise in. Choices D and E wisely dispense with the full clause and use a simple prepositional phrase. D, however, uses the imprecise in and the plural their. Only E, the best choice, avoids all the errors mentioned above.
OG175:状语比较_原因状语比较:
175. Two new studies indicate that many people become obese more due to the fact that their bodies burn calories too slowly than overeating.
(A) due to the fact that their bodies burn calories too slowly than overeating
(B) due to their bodies burning calories too slowly than to eating too much
(C) because their bodies bum calories too slowly than that they are overeaters
(D) because their bodies bum calories too slowly than because they eat too much
(E) because of their bodies burning calories too slowly than because of their eating too much
The members of a comparison (more X than Y) should be expressed in parallel form. D, the best choice, correctly uses parallel clauses introduced by because. The clauses them?selves are clear and direct. Choice E uses parallel forms, but the convoluted structures are awkward and wordy. Furthermore, the word bodies would need an apostrophe (bodies') since it is the logical subject of the gerund burning (that is, it answers the question, "Whose burning"). A, B, and C do not use parallel forms for the two members of the comparison. In addition, A and B use due to unidiomatically to mean because; properly used, due to is synonymous with attributable to.
E.特殊结构的比较 ==》这种比较类似于固定用法，有 than expected / than usual 等。
OG250: 特殊比较_ than expected
250. The company announced that its profits declined much less in the second quarter than analysts had expected it to and its business will improve in the second half of the year.
(A) had expected it to and its business will improve
(B) had expected and that its business would improve
(C) expected it would and that it will improve its business
(D) expected them to and its business would improve
(E) expected and that it will have improved its business
B, the best choice, avoids errors of agreement, correctly uses the parallel construction that x and that y, and uses would rather than will to refer to a promised but uncertain future event. In A and C, singular it after expected has no grammati?cal referent: its antecedent cannot be The company, but rather must be the plural profits. Choices A and C also contain errors of verb form, using will where would is required. Choices A and D fail to maintain parallel structure: properly formed, the construction would have that after expected to parallel that after announced. Furthermore, in D, the addition of them to is unnecessary. Choice E illogically uses the future perfect will have improved to suggest completion of an action that will be continuous in the second half of the year.
OG253:特殊比较_than usual
253.Analysts blamed May's sluggish retail sales on unexciting merchandise as well as the weather, colder and wetter than was usual in some regions. which slowed sales of barbecue grills and lawn furniture.
(A) colder and wetter than was usual in some regions, which slowed
(B) which was colder and wetter than usual in some regions, slowing
(C) since it was colder and wetter than usually in some regions, which slowed
(D) being colder and wetter than usually in some regions, slowing
(E) having been colder and wetter than was usual in some regions and slowed
Choice B is the best answer. It is concise and idiomatic, and which has a clear referent, the weather. In A, the insertion of was is unnecessary, and the referent of which is not clear because regions, not weather, is the nearest noun. In C, the adjective usual is needed in place of the adverb usually, and the referent of which is unclear because regions, not weather, is the nearest noun. In D and E, the verb phrases (being colder ..., having been colder . ..) do not refer as clearly to the noun weather as the pronoun which does. Choice D needs the adjective usual in place of the adverb usually, while choice E fails to maintain parallelism in verb tense (having been... and slowed).
例外：
OG46：主语比较_主谓宾句型
此题目是主谓宾全的主语比较结构，应该需要补出谓语动词。但是由于比较结构中的并列谓语require and gain 的出现，如果补出do 会造成不知道指向那里的歧义出现，为了表达清楚，所以省略了谓语动词。
46. A study commissioned by the Department of Agriculture showed that if calves exercise and associated with other calves, they will require less medication and gain weight quicker than do those raised in confinement.
(A) associated with other calves, they will require less medication and gain weight quicker than do
(B) associated with other calves, they require less medication and gain weight quicker than
(C) associate with other calves, they required less medication and will gain weight quicker than do
(D) associate with other calves, they have required less medication and will gain weight more quickly than do
(E) associate with other calves, they require less medication and gain weight more quickly than
Choice E, the best answer, uses the adverbial phrase more quickly than to modify the verb phrase gain weight. In A, B, and C, quicker than is incorrect because an adjective should not be used to modify a verb phrase. E is also the only choice with consistent verb tenses. The first verb in the clauses introduced by showed that is exercise. A and B incorrectly compound that present tense verb with a past tense verb, associated. C and D correctly use associate, but C follows with the past tense required and D with the present perfect have required. Both C and D incorrectly conclude with the future tense will gain.
2. as...as 结构
as...as 结构总体上分两种： as + adj. +as ; the same as...
其比较的主要的原则和more..than的结构是一样的,但是变化更多，GMAT更喜欢考。
A.主语比较 ==》比较原则是一样的，但是需要注意的是有一种特殊情况下，as adj. as 结构中的第二个as 会做代词做後一个比较结构的主语，从而从结构上看起来是只有宾语和谓语的比较。
#1 对于主谓宾全或者主谓+介宾短语的句子的主语比较，谓语动词必须补出，其主要目地是为了和宾语比较区分开来，防止歧义。
as+adj.+as 的比较结构的主语比较更复杂，有时候会把宾语放在as..as 之间，形成as +adj.+宾语+as 的结构，这种形式上看起来是只有主谓句的比较，实质上是主谓宾全的句子，需要补出谓语。
例 OG89： 主语比较_主谓宾句型
主语比较_主谓宾_as+adj.+as_there be 完整句
89. A recent national study of the public schools shows that there are now one microcomputer for every thirty-two pupils, four times as many than there were four years ago.
(A) there are now one microcomputer for every thirty-two pupils, four times as many than there were
(B) there is now one microcomputer for every thirty-two pupils, four times as many than there were
(C) there is now one microcomputer for every thirty-two pupils, four times as many as there were
(D) every thirty-two pupils now have one micro?computer, four times as many than there were
(E) every thirty-two pupils now has one microcom?puter, four times as many as
Choices A, B, and C appropriately use the construction "one X for every thirty-two Y's" to describe the ratio of computers to pupils, but only C, the best answer, is error-free. In A, are does not agree with the subject, one microcomputer; furthermore, in A, B, and D, than is used where as is required. Choices D and E reorder and garble the "one X ..." construction, making four times as many refer illogically to pupils.
主语比较_主谓宾_as+adj.+宾语+as
168. Today, because of improvements in agricultural technology, the same amount of acreage produces double the apples that it has in 1910.
(A) double the apples that it has
(B) twice as many apples as it did
(C) as much as twice the apples it has
(D) two times as many apples as there were
(E) a doubling of the apples that it did
Choice B, the best answer, correctly uses the adverbial phrase twice as many... to modify the verb produces; properly employs many rather than much to describe a quantity made up of countable units (apples); and appropriately substitutes did for the understood produced to express the logically necessary past tense of produces. Choice A awkwardly substitutes the adjective double for twice; uses that without a clear referent; and misuses has to refer to events occurring in 1910. Choice C employs the incorrect much in a wordy construction and also misuses has. D is wordy and imprecise;... as there were in 1910 refers to all apples produced in 1910, regardless of location. E is illogical: since that refers to a doubling, E nonsensically asserts that the doubling occurred in 1910.
主语比较_主谓宾_as+adj.+不定式宾语+as
156. Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much as maintaining paved roads.
(A) dirt roads cost twice as much as maintaining paved roads
(B) dirt roads cost twice as much to maintain as paved roads do
(C) maintaining dirt roads costs twice as much as paved roads do
(D) maintaining dirt roads costs twice as much as it does for paved roads
(E) to maintain dirt roads costs twice as much as for paved roads
This sentence compares the costs required to maintain two kinds of roads. B, the best choice, is able to maintain parallelism in the comparison as well. Choice A incorrectly shifts the meaning by comparing the cost of dirt roads with the cost of maintaining paved roads. Choice C does the opposite: it compares the cost of maintaining dirt roads with the cost of paved roads themselves. Choice D further confuses the sentence by adding a nonparallel clause, it does for, in which it has no clear referent. Choice E introduces the infinitive phrase to maintain... and wrongly attempts to complete the comparison with the nonparallel prepositional phrase for....
但是当A do as +adj.+宾语+as B do 变成 A do as +adj.+ as+ B +不定式, 谓语动词省略. GWD/Prep有这种类型的题目。
主语比较_主谓宾_as+adj.+不定式宾语+as
265. Thomas Eakins' powerful style and his choices of subject--the advances in modern surgery, the discipline of sport, the strains of individuals in tension with society or even with themselves--was as disturbing to his own time as it is compelling for ours.
(A) was as disturbing to his own time as it is
(B) were as disturbing to his own time as they are
(C) has been as disturbing in his own time as they are
(D) had been as disturbing in his own time as it was
(E) have been as disturbing in his own time as
Choice B, the best answer, exhibits correct subject-verb agreement and uses appropriate verb tenses. Choices A, C, and D contain errors of agreement: the compound subject style and... choices of subject requires a plural verb and should correspond to the plural pronoun they, not it. Further?more, C wrongly shifts to the present perfect tense (has been) to characterize something that happened in the past, while D uses the past tense was to characterize something that is happening in the present. In E, while the plural have agrees in number with the compound subject, the use of the present perfect tense (have been) is inappropriate for characterizing the effect of Eakins' work in his own time.
#2 对于主系表或者主谓+其他非名词性结构修饰成分的句子的主语比较，由于谓语动词之后不存在名词性结构造成歧义，谓语动词省略。
主语比较_主谓_as...as
149. Last year, land values in most parts of the pinelands rose almost so fast. and in some parts even faster than what they did outside the pinelands.
(A) so fast, and in some parts even faster than what they did
(B) so fast, and in some parts even faster than, those
(C) as fast, and in some parts even faster than, those
(D) as fast as, and in some parts even faster than, those
(E) as fast as, and in some parts even faster than what they did
The properly completed sentence here must (1) use the proper form of the comparative conjunction, as fast as; (2) enclose the parenthetical statement and... even faster than in commas; and (3) preserve parallel structure, clarity of reference, and economy by using those to substitute for land values in the completed comparison. D, the best choice, does all these things correctly. A and B use so unidiomatically in place of as. A and E omit the comma needed after than and use the confusing and unparallel what they did instead of those. C omits the second as needed in the comparative conjunction as fast as.
3# as...as 结构中有一种特殊结构是在第二个as 做代词的情况下，此时比较的前后都是完整的句子。
主语比较_主谓_as做代词_as..as
187. In one of the bloodiest battles of the Civil War, fought at Sharpsburg, Maryland, on September 17, 1862, four times as many Americans were killed as would later be killed on the beaches of Normandy during D-Day.
(A) Americans were killed as
(B) Americans were killed than
(C) Americans were killed than those who
(D) more Americans were killed as there
(E) more Americans were killed as those who
Choice A, the best answer, is the only option that accurately expresses the comparison by using the idiomatic form as many... as. In B and C, as many ... than is unidiomatic, and in C and E, those who is a wordy intrusion. In D and E, more is redundant because the phrase four times as many in the original sentence conveys the idea of more.
主语比较_主谓_as做代词_as..as
132. According to a study by the Carnegie Foundation for the Advancement of Teaching, companies in the United States are providing job training and general education for nearly eight million people, about equivalent to the enrollment of the nation's four-year colleges and universities.
(A) equivalent to the enrollment of
(B) the equivalent of those enrolled in
(C) equal to those who are enrolled in
(D) as many as the enrollment of
(E) as many as are enrolled in
The phrases equivalent to in A, the equivalent of in B, and equal to in C have too broad a range of meanings to be used precisely here: that is, they can suggest more than merely numerical equality. Also, as quantitative expressions, equiva?lent and equal often modify nouns referring to uncountable things, as in "an equivalent amount of resistance" or "a volume of water equal to Lake Michigan." To establish numerical comparability between groups with countable members, the phrase as many as is preferable. Choice D, however, uses this phrase improperly in comparing eight million people to enrollment, not to other people. The comparison in E, the best choice, is logical because people is understood as the subject of are enrolled.
B.宾语比较 ==》这种比较之存在于主谓宾全的句子中。需要和主谓宾全的句子的主语比较 以及 介宾结构的比较区分。
另外一点需要注意的是这种比较的宾语通常用代词+介词+对应的主语比较对象组成，需要和主谓宾全的句子的主语比较区分。
宾语比较_主谓宾_as..as
266. In a recent poll, 86 percent of the public favored a Clean Air Act as strong or stronger than the present act.
(A) a Clean Air Act as strong or stronger than
(B) a Clean Air Act that is stronger, or at least so strong as,
(C) at least as strong a Clean Air Act as is
(D) a Clean Air Act as strong or stronger than is
(E) a Clean Air Act at least as strong as
E, the best choice, is concise, clear, and idiomatic. Choices A, B, C, and D may be faulted for constructions that are cumber?some, unnecessarily wordy, or unidiomatic. Choices A and D require as strong as instead of as strong. Similarly, B is missing than after stronger, and so should be as. In C and D, is should be dropped. Even with revisions, these choices are more wordy and awkward than the best answer.
D.状语的比较
注意在存在可能歧义的情况下，补出最完整的句子结构是Prefer的。
状语比较_主谓宾_完整句_as+adj.+宾语+as
92. Never before had taxpayers confronted so many changes at once as they had in the Tax Reform Act of 1986.
(A) so many changes at once as they had in
(B) at once as many changes as
(C) at once as many changes that there were with
(D) as many changes at once as they confronted in
(E) so many changes at once that confronted them in
Choice D is the best answer, stating grammatically and clearly that, with the 1986 Tax Reform Act, taxpayers confronted more simultaneous changes than ever before. In choice A, the past perfect had [confronted] illogically places the 1986 events in the same time frame as Never before had...; a simple past tense is needed to present the 1986 events as following the earlier ones. Choices B and C awkwardly place at once between confronted and its direct object, changes. Furthermore, B illogically states that the Act itself was many changes, when the point is rather that it presented many changes, and as many ... that is an unidiomatic comparison. Choice E, too, presents an unidiomatic comparison with so many... that.
特殊：the same as：
the same as 也符合比较结构的大的原则：
主语比较_主谓_the same as
80. Salt deposits and moisture threaten to destroy the Mohenjo-Daro excavation in Pakistan, the site of an ancient civilization that flourished at the same time as the civilizations in the Nile delta and the river valleys of the Tigris and Euphrates.
(A) that flourished at the same time as the civilizations
(B) that had flourished at the same time as had the civilizations
(C) that flourished at the same time those had
(D) flourishing at the same time as those did
(E) flourishing at the same time as those were
Choice A, the best answer, uses the simple past tense flourished to describe civilizations existing simultaneously in the past. Choice B wrongly uses the past perfect had flourished; past perfect tense indicates action that was completed prior to some other event described in the simple past tense: for example, "Mayan civilization had ceased to exist by the time Europeans first reached the Americas." Choice C lacks as after time. In choices C, D, and E, the plural pronoun those has no plural noun to which it can refer. In C, had signals the incorrect past perfect; did in D and were in E are awkward and unnecessary. D and E also incorrectly use the present participle flourishing where that flourished is needed.
3. Like+n. 与 as+句子的比较结构
关于Like+n. 和 as+句子的这种比较结构，也是ＧＭＡＴ perfer 的考点之一。其重点就是快速判断除like / as 对应的比较对象是否合理，从而排除选项。
like / as的差别就在于Like 后面只能接名词性结构，而 as 后面的必须是完整的句子或者不引起歧义下的省略成分，但是不能是简单的名词性结构。
当Like和as都同时可以使用的时候， like+n.是更加简洁的结构，因此GMAT更加perfer.
一。like+n. 比较结构
like+n. 的比较通常放在句首，其比较对象是句子的主语。因此看到这类型的题目首先判断的就是对应的主语是否和like后面接的名词是对等的对象。
但是，需要注意的是，like+n.结构也能放在句中或这句末，在OG和PrepSC中都有这样的题目。其原则就是不能有歧义出现。
关于这一点，有大N的帖子：http://forum.chasedream.com/dispbbs.asp?BoardID=23&ID=48608
主语比较_like/unlike_前置
16. Unlike a typical automobile loan, which requires a fifteen- to twenty-percent down payment, the lease-loan buyer is not required to make an initial deposit on the new vehicle.
(A) the lease-loan buyer is not required to make
(B) with lease-loan buying there is no requirement of
(C) lease-loan buyers are not required to make
(D) for the lease-loan buyer there is no requirement of
(E) a lease-loan does not require the buyer to make
Choice E, the best answer, correctly uses a parallel construction to draw a logical comparison: Unlike a typical automobile loan,... a lease-loan.... Choice A illogically compares an automobile loan, an inanimate thing, with a lease-loan buyer, a person. In choice C, buyers makes the comparison inconsistent in number as well as illogical. Choices B and D are syntactically and logically flawed because each attempts to compare the noun loan and a prepositional phrase: with lease-loan buying in B and/or the lease-loan buyer in D. Choices B and D are also imprecise and awkward. Finally, choice E is the only option that supplies an active verb form, does not require, to parallel requires.
主语比较_like/unlike_主系表
51. While Jackie Robinson was a Brooklyn Dodger, his courage in the face of physical threats and verbal attacks was not unlike that of Rosa Parks, who refused to move to the back of a bus in Montgomery, Alabama.
(A) not unlike that of Rosa Parks, who refused
(B) not unlike Rosa Parks, who refused
(C) like (Rosa Parks and her refusal
(D) like that of Rosa Parks for refusing
(E) as that of Rosa Parks, who refused
Choices B and C present faulty comparisons: in B, Jackie Robinson's courage is compared to Rosa Parks herself, not to her courage, and in C it is compared to both Rosa Parks and her refusal. Choice D does not make clear whether it was Jackie Robinson or Rosa Parks who showed courage in refusing to move to the back of the bus; in fact, saying for refusing rather than who refused makes it sound as if courage moved to the back of the bus. Choice E incorrectly uses as rather than like to compare two noun phrases. Choice A is best.
主语比较_like/unlike_前置
91. Like many self-taught artists, Perle Hessing did not begin to paint until she was well into middle age.
(A) Like
(B) As have
(C) Just as with
(D) Just like
(E) As did
Choice A, the best answer, is concise and grammatically correct, using the comparative preposition like to express the comparison between many self-taught artists and Perle Hessing. Choices B and E, which replace A's prepositional phrase with clauses introduced by as, use auxiliary verbs that cannot properly be completed by any part of the verb phrase in the main clause: neither have ... did not begin nor did... did not begin is logically or grammatically sound. In C and D, Just as with and Just like are both unnecessarily wordy.
主语比较_like/unlike_前置
193. Unlike the United States, where farmers can usually depend on rain or snow all year long. the rains in most parts of Sri Lanka are concentrated in the monsoon months, June to September, and the skies are generally clear for the rest of the year.
(A) Unlike the United States, where farmers can usually depend on rain or snow all year long, the rains in most parts of Sri Lanka
(B) Unlike the United States farmers who can usually depend on rain or snow all year long, the rains in most parts of Sri Lanka
(C) Unlike those of the United States, where farmers can usually depend on rain or snow all year long, most parts of Sri Lanka's rains
(D) In comparison with the United States, whose farmers can usually depend on rain or snow all year long, the rains in most parts of Sri Lanka
(E) In the United States, farmers can usually depend on rain or snow all year long, but in most parts of Sri Lanka the rains
In comparative structures (unlike X, Y...; in comparison with X,Y...) X and Y must be both logically and grammatically parallel. Choices A, B, C, and D all fail to observe logical parallelism: (A) Unlike the United States,... the rains...; (B) Unlike the United States farmers .. . , the rains .. . ; (C) Unlike those of the United States, . . . most parts of Sri Lanka's rains ... ; and (D) In comparison with the United States,... the rains... . C also suffers from the unintelli?gible most parts of Sri Lanka's rains. E, the best choice, avoids the problem by using two independent clauses linked by but to present a clear, direct contrast between conditions in the United States and those in most parts of Sri Lanka.
主语比较_like/unlike_前置
206. Like Auden. the language of James Merrill is chatty, arch, and conversational--given to complex syntactic flights as well as to prosaic free-verse strolls.
(A) Like Auden, the language of James Merrill
(B) Like Auden, James Merrill's language
(C) Like Auden's, James Merrill's language
(D) As with Auden, James Merrill's language
(E) As is Auden's the language of James Merrill
At issue is a comparison of Auden's language with Merrill's language. Only C, the best choice, uses the elliptical like Auden's (language being understood), to compare Auden's language with Merrill's language. A, B, and D compare Auden (the person) with Merrill's language. Choice E is awkward and unidiomatic.
主语比较_like/unlike_前置
232. Unlike auto insurance, the frequency of claims does not affect the premiums for personal property coverage, but if the insurance company is able to prove excessive loss due to owner negligence, it may decline to renew the policy.
(A) Unlike auto insurance, the frequency of claims does not affect the premiums for personal property coverage
(B) Unlike with auto insurance, the frequency of claims do not affect the premiums for personal property coverage
(C) Unlike the frequency of claims for auto insurance, the premiums for personal prop?erty coverage are not affected by the frequency of claims
(D) Unlike the premiums for auto insurance, the premiums for personal property coverage are not affected by the frequency of claims
(E) Unlike with the premiums for auto insurance, the premiums for personal property coverage is not affected by the frequency of claims
Choice D, the best answer, correctly and clearly compares the premiums for auto insurance and the premiums for personal property coverage. Choices A and C fail to express this comparison: A illogically compares auto insurance and the frequency of claims, and C illogically compares the frequency of claims and premiums. Unlike with in choices B and E is an unidiomatic form of comparison. In B, the plural do not affect fails to agree with frequency; in E, the singular is does not agree with premiums.
主语比较_like/unlike_前置
245. Unlike Schoenberg's twelve-tone system that dominated the music of the postwar period, Bartok founded no school and left behind only a handful of disciples.
(A) Schoenberg's twelve-tone system that dominated
(B) Schoenberg and his twelve-tone system which dominated
(C) Schoenberg, whose twelve-tone system dominated
(D) the twelve-tone system of Schoenberg that has dominated
(E) Schoenberg and the twelve-tone system, dominating
C, the best answer, is the only choice that makes a logical comparison: Unlike Schoenberg, .. . Bartok. In A, B, and D, Bartok, a person, is compared either to Schoenberg's twelve-tone system or to Schoenberg and his twelve-tone system as a unit. Such comparisons are neither logically sound nor seman-tically parallel. Consequently, A and D illogically suggest that Schoenberg's twelve-tone system founded a school and left behind many disciples. Choice B suggests that Schoenberg and his twelve-tone system together accomplished these feats. In E, the comparison is illogical and the modification is ambiguous. Schoenberg and his system, as a unit, are not only compared to Bartok, an individual, but also credited with having formed a school. The verb phrase dominating ... is called a "squinting modifier" because it looks in both direc?tions: given the structure of the sentence, it could be meant to modify either Schoenberg and the twelve-tone system or Bartok.
主语比较_like/unlike_前置
267. Like Rousseau. Tolstoi rebelled against the unnatural complexity of human relations in modern society.
(A) Like Rousseau, Tolstoi rebelled
(B) Like Rousseau, Tolstoi's rebellion was
(C) As Rousseau, Tolstoi rebelled
(D) As did Rousseau, Tolstoi's rebellion was
(E) Tolstoi's rebellion, as Rousseau's, was
In choice A, the best answer, a clear and logical comparison is made between Rousseau and Tolstoi. Choice B illogically compares a person, Rousseau, to an event, Tolstoi's rebellion. Also, Tolstoi's rebellion was against is less direct than Tolstoi rebelled against. Inserting did after As would make C gram?matical. Because As is a conjunction, it must introduce a clause; hence the noun Rousseau must have a verb. Choice D compares an implied action (As did Rousseau) with a noun (Tolstoi's rebellion). Choice E is awkwardly formed, and like is needed in place of as to compare two nouns (rebellion is understood after Rousseau's). Also, Tolstoi's rebellion... was against is less direct than Tolstoi rebelled against.
主语比较_like/unlike_后置
189. Proponents of artificial intelligence say they will be able to make computers that can understand English and other human languages, recognize objects, and reason as an expert does-computers that will be used to diagnose equipment breakdowns, deciding whether to authorize a loan, or other purposes such as these.
(A) as an expert does--computers that will be used to diagnose equipment breakdowns, deciding whether to authorize a loan, or other purposes such as these
(B) as an expert does, which may be used for purposes such as diagnosing equipment breakdowns or deciding whether to authorize a loan
(C) like an expert--computers that will be used for such purposes as diagnosing equipment breakdowns or deciding whether to authorize a loan
(D) like an expert, the use of which would be for purposes like the diagnosis of equipment breakdowns or the decision whether or not a loan should be authorized
(E) like an expert, to be used to diagnose equipment breakdowns, deciding whether to authorize a loan or not, or the like
A correct sentence must maintain parallel structure. In choice A, the three-part series (to diagnose ..., deciding,... or other purposes ...) lacks parallelism. C, the best choice, replaces A's third element with/or such purposes as; this phrase functions as a stem for the other two elements, which are recast as two parallel phrases--diagnosing ... or deciding .... Thus, choice C not only manages the parallel structure but avoids the less effective other purposes such as these at the end of choice A. Choice E uses faulty parallel structure (to be used..., deciding ..., or the like). In B and D, which and the use of which introduce sentence elements that lack antecedents or reference. In addition, D is wordy.
二 as+句子 比较结构
as + 句子的比较结构和like+n.的用法类似，但是as 后面不能接简单的名词性结构。
介宾比较_as+从句_完整句
60. According to a recent poll, owning and living in a freestanding house on its own land is still a goal of a majority of young adults, like that of earlier generations.
(A) like that of earlier generations
(B) as that for earlier generations
(C) just as earlier generations did
(D) as have earlier generations
(E) as it was of earlier generations
The intended comparison should be completed by a clause beginning with as and containing a subject and verb that correspond to the subject and verb of the main clause. In E, the best choice, it refers unambiguously to the phrasal subject owning ... land, the verb was corresponds to is, and today's young adults are appropriately compared to earlier generations. Choices A and B lack a verb corresponding to is and a clear referent for that. Choices C and D are confusing and illogical because their verbs, did and have, cannot substitute for is in the main clause.
4. 其他，如rather than, instead of, etc....
除1-3中的比较结构之外，还有一些结构或者比较词引导的特殊类型的比较结构。这些比较结构在GMAT中出现相对较少，但是同样需要掌握。
the more...the more结构
7. Dr. Hakuta's research among Hispanic children in the United States indicates that the more the children use both Spanish and English, their intellectual advantage is greater in skills underlying reading ability and nonverbal logic.
(A) their intellectual advantage is greater in skills underlying reading ability and nonverbal logic
(B) their intellectual advantage is the greater in skills underlaying reading ability and nonverbal logic
(C) the greater their intellectual advantage in skills underlying reading ability and nonverbal logic
(D) in skills that underlay reading ability and nonverbal logic, their intellectual advantage is the greater
(E) in skills underlying reading ability and nonverbal logic, the greater intellectual advantage is theirs
The best choice is C. The phrase the more the children should be completed by a parallel phrase that begins with a compara?tive adjective and a noun phrase, as in the greater their... advantage. Only C correctly completes the structure with a parallel phrase. Choices A. B, D, and E present structures that are unwieldy and awkward in addition to being nonparallel, and that state the relationship between language use and skills development less clearly than C does. Also, underlaying in B and underlay in D are incorrect; the meaning of this sentence requires the present participle of "underlie," underlying, as a modifier of skills.
resemble_宾语比较
167. Neanderthals had a vocal tract that resembled those of the apes and so were probably without language, a shortcoming that may explain why they were supplanted by our own species.
(A) Neanderthals had a vocal tract that resembled those of the apes
(B) Neanderthals had a vocal tract resembling an ape's
(C) The vocal tracts of Neanderthals resembled an ape's
(D) The Neanderthal's vocal tracts resembled the apes’
(E) The vocal tracts of the Neanderthals resembled those of the apes
The sentence requires a subject appropriate to both members of a compound predicate, the second member being and so were probably without language. B, the best choice, logically uses Neanderthals as the subject. Choice A also uses this subject, but the plural pronoun those does not agree with its singular antecedent, a vocal tract. C, D, and E present the inappropriate subject vocal tracts, which cannot logically govern the second member of the predicate (i.e., vocal tracts cannot be said to be without language). Moreover, it is better to use the singular in referring to an anatomical feature common to an entire species; C, D, and E use the plural vocal tracts. D compounds the problem by giving multiple vocal tracts to one Neanderthal.
Rather than
264. Scientists believe that unlike the males of most species of moth, the male whistling moths of Nambung, Australia, call female moths to them by the use of acoustical signals, but not olfactory ones, and they attract their mates during the day, rather than at night.
(A) by the use of acoustical signals, but not olfactory ones, and they attract
(B) by the use of acoustical signals instead of using olfactory ones, and attracting
(C) by using acoustical signals, not using olfactory ones, and by attracting
(D) using acoustical signals, rather than olfactory ones, and attract
(E) using acoustical signals, but not olfactory ones, and attracting
Choice D, the best answer, is concise, maintains parallel structure, and clearly conveys the comparisons being made between the two types of moth. In A and E, the comparison between most male moths and the male whistling moth is not clear. The use of but not does not clearly convey that most other moths use olfactory signals; rather than would be preferable, as well as parallel to rather than at night. In A, the phrase by the use of is unnecessarily wordy, and the insertion of they is not required. In E, the final verb should be attract (parallel to call), not attracting (parallel to using). Choice B violates parallelism with by the use of... instead of using, as well as with call... and attracting. Choice C distorts the meaning of the original with its suggestion that male whistling moths call female moths to them both by using acoustical signals and by attracting their mates during the day. The insertion of using in not using olfactory ones is unnecessary.
比较的最高级
26. Of all the possible disasters that threaten American agriculture, the possibility of an adverse change in climate is maybe the more difficult for analysis.
(A) is maybe the more difficult for analysis
(B) is probably the most difficult to analyze
(C) is maybe the most difficult for analysis
(D) is probably the more difficult to analyze
(E) is, it may be, the analysis that is most difficult
Choice B is the best answer. The sentence compares one thing, an adverse change in climate, to all other things in its class-- that is, to all the possible disasters that threaten American agriculture, therefore, the sentence requires the superlative form of the adjective, most difficult, rather than the comparative form, more difficult, which appears in choices A and D. In A and C, the use of maybe is unidiomatic, and difficult should be completed by the infinitive to analyze. Choice E is awkwardly phrased and, when inserted into the sentence, produces an illogical structure: the possibility ... is... the analysis that.
5. 与比较有关或者容易混淆的结构。
在ＧＭＡＴ中还有一些结构是和比较有关的，而且和通常的比较结构容易混淆。
尤其是在as 的使用上，由于有很多as组成的固定搭配和as做其他成分的使用方法，复习时需要注意和比较的结构区分开。
下面是一些例子：
No less than
30. What was as remarkable as the development of the compact disc has been the use of the new technology to revitalize, in better sound than was ever before possible, some of the classic recorded performances of the pre-LP era.
(A) What was as remarkable as the development of the compact disc
(B) The thing that was as remarkable as developing the compact disc
(C) No less remarkable than the development of the compact disc
(D) Developing the compact disc has been none the less remarkable than
(E) Development of the compact disc has been no less remarkable as
Besides being wordy, the clauses beginning What was in A and The thing that was in B cause inconsistencies in verb tense: the use of the new technology cannot logically be described by both the present perfect has been and the past was. In B and D, developing the compact disc is not parallel to the use of new technology to revitalize ... performances; in C, the best answer, the noun development is parallel to use. The phrases none the less ... than in D and no less... as in E are unidiomatic; the correct form of expression, no less ... than, appears in C, the best choice.
the figure_平行
81. In 1973 mortgage payments represented twenty-one percent of an average thirty-year-old male's income; and forty-four percent in 1984.
(A) income; and forty-four percent in 1984
(B) income; in 1984 the figure was forty-four percent
(C) income, and in 1984 forty-four percent
(D) income, forty-four percent in 1984 was the figure
(E) income that rose to forty-four percent in 1984
To establish the clearest comparison between circumstances in 1973 and those in 1984, a separate clause is needed to describe each year. Choices A and C, in failing to use separate clauses, are too elliptical and therefore unclear. Choice A also incor?rectly uses and and a semicolon to separate an independent clause and a phrase. Choice D incorrectly separates two independent clauses with a comma; moreover, the placement of in 1984 is awkward and confusing. In choice E, that refers illogically to income, thereby producing the misstatement that income rather than mortgage payments rose to forty-four percent in 1984. Choice B is best; two properly constructed clauses that clearly express the comparison are separated by a semicolon.
use...as_固定搭配
120. The Parthenon was a church from 1204 until 1456, when Athens was taken by General Mohammed the Conqueror, the Turkish sultan, who established a mosque in the building and used the Acropolis as a fortress.
(A) who established a mosque in the building and used the Acropolis as
(B) who, establishing a mosque in the building, used the Acropolis like
(C) who, when he had established a mosque in the building, used the Acropolis like
(D) who had established a mosque in the building, using the Acropolis to be
(E) establishing a mosque in the building and using the Acropolis as
Choice A, the best answer, correctly supplies the past tense verbs established and used to describe two actions performed in 1456; also, it idiomatically employs the phrase used the Acropolis as a fortress, in which used as means "employed in the capacity of." Choices B and C incorrectly replace as wiui like. Furthermore, in C, when he had established a mosque distorts the intended meaning by stating that the first action was completed before the second was begun. Similarly, in D, had established... using states that Mohammed had already performed the actions before capturing Athens; and in E, establishing and using modify Athens, thus producing an absurd statement. In addition, D includes the unidiomatic construction "using x to be y."
as_表示原因
207. In the textbook publishing business, the second quarter is historically weak, because revenues are low and marketing expenses are high as companies prepare for the coming school year.
(A) low and marketing expenses are high as companies prepare
(B) low and their marketing expenses are high as they prepare
(C) low with higher marketing expenses in preparation
(D) low, while marketing expenses are higher to prepare
(E) low, while their marketing expenses are higher in preparation
A, the best choice, correctly balances the contrasting terms low and high in parallel form (adjectives in the positive degree). It also makes clear who, exactly, is preparing for the coming school year (companies). B uses the plural pronouns their and they without an appropriately stated referent. C, D, and E violate the parallelism needed for the contrasting terms by making the second term an adjective in the com?parative degree (higher). Furthermore, the use of higher without a stated point of comparison makes it unclear what the expenses are higher than. E also uses the pronoun their without an appropriate referent.
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