GMAT考试-GWD-CR解析-ASSUMPTION

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GWD-1-Q40:
Until Now, only injectable vaccines against influenza have been available.  Parents are reluctant to subject children to the pain of injections, but adults, who are at risk of serious complications from influenza, are commonly vaccinated.  A new influenza vaccine, administered painlessly in a nasal spray, is effective for children.  However, since children seldom develop serious complications from influenza, no significant public health benefit would result from widespread vaccination of children using the nasal spray.

Which of the following is an assumption on which the argument depends?

A.        Any person who has received the injectable vaccine can safely receive the nasal-spray vaccine as well.
B.        The new vaccine uses the same mechanism to ward off influenza as jnjectable vaccines do.
C.        The injectable vaccine is affordable for all adults.
D.        Adults do not contract influenza primarily from children who have influenza.排除削弱。原来说给小孩注射这种新疫苗对公众健康不会有多大好处，现在就说有好处来削弱。或者理解成GAP。children seldom develop serious complications from influenza = no significant public health benefit弥补这个GAP。这里有一个分类小孩和大人。结论只考虑了小孩，从大人入手。
E.        The nasal spray vaccine is mot effective when administered to adults.[D]

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T-9-Q19. 天山-7-11
In 1992 outlaw fishing boats began illegally harvesting lobsters from the territorial waters of the country of Belukia. Soon after, the annual tonnage of lobster legally harvested in Belukian waters began declining; in 1996, despite there being no reduction in the level of legal lobster fishing activity, the local catch was 9,000 tons below pre-1992 levels. It is therefore highly likely that the outlaw fishing boats harvested about 9,000 tons of lobster illegally that year.
确切数字的比较。捕获量减少的部分恰是非法捕获的数量。引入其他的捕获量
此消彼长的关系的前提：总量不变。（OG政府加税恶性循环那道）
Which of the following is an assumption on which the argument depends?

A.        The illegal lobster harvesting was not so extensive that the population of catchable lobsters in Belukia’s territorial waters had sharply declined by 1996 A的意思是，非法捕捞并没有多到让龙虾数量急剧减少的程度。这样就正好说明了题意，因为龙虾总数量不变，合法捕捞减少的龙虾数量就正好被非法捕捞的人给弄走了。如果龙虾总数变了，非法捕获和合法捕获数量之间的比较就不确定了。
B.        The average annual lobster catch, in tons, of an outlaw fishing boat has increased steadily since 1992.（反题意）
C.        Outlaw fishing boats do not , as a group, harvest more lobsters than do licensed lobster-fishing boats.
D.        The annual legal lobster harvest in Belukia in 1996 was not significantly less than 9,000 tons. 是比1992年少了9000，不是比9000少
E.        A significant proportion of Belukia’s operators of licensed lobster-fishing boats were out of business between 1992 and 1996

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T-9-Q4.
In the years following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent. In contrast, in the year prior to the tax increase, sales had fallen one percent. The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.
（Pretax price + tax）*volume=sale
The argument above requires which of the following assumptions?

A.        During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase. 是税前价和税后价比较而不是两年间价格增幅的比较。A极具迷惑性
B.        The one percent fall in cigarette sales in the year prior to tax increases was due to a smaller tax increase. Strengthen
C.        The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase. Stregnthen
D.        For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year. 那么税前裸价的下降抵消了税的增长，括号部分没有变化。不是括号的部分，也就是税后价格导致了Sales的变化。（排除此消彼长的可能）
E.        As the after-tax price of a pack of cigarettes rises, the pretax price also rises.

论题是税费增加第二年香烟销量减少10%和税后价格增加有关，题目给出信息是税费每合增加8分，但税前裸价变化没有信息，而税后价和这2者都有关系。于是D中给出了补充信息：第二年税前裸价并不比前年低8美分或以上，也就是说税前裸价没有下降到足以抵消税费增加的幅度，可能是降了5美分，甚至也可能是裸价提高了。这样得出的结论是第二年每合税后总价格（裸价+税费）确实是增加了，从而引起香烟销量剧降。
首先把选项取非, 也就是说价格的增加超过税率增加前的价格增加. 可以发现, 税率增加后的情况是税率增加了, 价格也增加了, 他们共变导致了10%的销售量的下降; 由于A默认了价格的增加会导致销售量的下降, 所以如果我现在假设一种情况, 即销售价格增幅很大, 达到可以几乎不考虑税率的区区8分, 而这个大幅增加导致了销售量的大幅减少, 这样, 无法确定这区区8分税率的变化究竟是否有影响.
提炼一步:
税率*裸价=价格---销售量(中间的"---"表示"推倒出")
简化就是:
{税率*裸价}---销售量
答案A给出的以上三者同方向变化, 无法证明任何东西.
推广一步: <物理学实验证明方法论>里面有一条: 等式量变如果存在相同方向的共变, 无法证明不变的其它因素是否产生影响.
注意谁跟谁比：是“加税以后的税前价”跟“加税前的税前价”比较，
而不是“加税后的税前价的增幅”跟“加税前的税前价的增幅”进行比较
For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year. —>取非：税前价格比前一年要低八分钱，那么加上增加的税收八分钱，则今年加税的税后价格与去年的税后价格相同，那么今年的销售下降10%的原因就不一定是加税后的税后价格了

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T-4-Q34
In Kravonia, the average salary for jobs requiring a college degree has always been higher than the average salary for jobs that do not require a degree. Current enrollments in Kravonia’s colleges indicate that over the next four years the percentage of the Kravonian workforce with college degree will increase dramatically. Therefore, the average salary for all workers in Kravonia is likely to increase over the next four years.
大学学位导致平均工资高。
Which of the following is an assumption on which the argument depends?
A.        Kravonians with more than one college degree earn more, on average, than do Kravonians with only one college degree.
B.        The percentage of Kravonians who attend college in order to earn higher salaries is higher now than it was several years ago.
C.        The higher average salary for jobs requiring a college degree is not due largely to a scarcity among the Kravonian workforce of people with a college degree.她因。文章结论学历高----工资高；排除学历稀有性----工资高
D.        The average salary in Kravonia for jobs that do not require a college degree will not increase over the next four years.
E.        Few members of the Kravonian workforce earned their degrees in other countries.

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GWD24
35
The milk of many mammals contains cannabinoids, substances that are known to stimulate certain receptors in the brain. To investigate the function of cannabinoids, researchers injected newborn mice with a chemical that is known to block cannabinoides from reaching their receptors in the brain. The injected mice showed far less interest in feeding than normal newborn mice do. Therefore, cannabinoids probably function to stimulate the appetite.
牛奶里面有小C能够刺激大脑中的Receptor。
在新生老鼠里面注入抑制小C的化学物质不让他接触大脑中的Receptor
实验结果：被注射的老鼠食欲不振
结论：小C刺激食欲。
Which of the following is an assumption on which the argument depends?
A.        Newborn mice do not normally ingest any substance other than their
mothers’ milk.
B.        Cannabinoids are the only substances in mammals’ milk that stimulate the appetite. 取非，牛奶中还有其它物质刺激食欲。不能削弱小C刺激食欲的可能性：就算还有其他成分刺激食欲，抑制了C，还是会使整体食欲下降
C.        The mothers of newborn mice do not normally make any effort to encourage their babies to feed.
D.        The milk of mammals would be less nutritious if it did not contain cannabinoids.
E.        The chemical that blocks cannabinoids from stimulating their brain receptors does not independently inhibit the appetite. 排除他因。他因：是化学物质而不是小C抑制了食欲。

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GWD-13-Q38: Frobisher, a sixteenth-century English explorer, had soil samples from Canada’s Kodlunarn Island examined for gold content.  Because high gold content was reported, Elizabeth I funded two mining expeditions.  Neither expedition found any gold there.  Modern analysis of the island’s soil indicates a very low gold content.  Thus the methods used to determine the gold content of Frobisher’s samples must have been inaccurate.
F金矿检测法不准确。

Which of the following is an assumption on which the argument depends?

A.        The gold content of the soil on Kodlunarn Island is much lower today than it was in the sixteenth century. F检测法用于过去，不应该以现在的标准衡量。另外A再说其实过去的含金量很高，反文中所提到的Neither expedition found any gold there. 此外，还应该是削弱结论。说这个检测法是正确的。
B.        The two mining expeditions funded by Elizabeth I did not mine the same part of Kodlunarn Island.
C.        The methods used to assess gold content of the soil samples provided by Frobisher were different from those generally used in the sixteenth century.
D.        Frobisher did not have soil samples from any other Canadian island examined for gold content. 反文中前提：Frobisher had soil samples from Canada’s Kodlunarn Island examined for gold content.  
E.        Gold was not added to the soil samples collected by Frobisher before the samples were examined.
If E can stands the point, it is the content itself not the method is inaccurate   样本本身有问题而不是方法有问题
将E取非，在样品检验前F放金在样品中。这样F的样品含金高而实际不高的原因就不是方法不对了。结论说方法不对就不成立。故为假设。
易混的是D。好像也是排除他因。但原文说的是检验K岛的金含量。其他岛的情况无关。选D的原因在于认为F用其它岛的样品充当K岛样品。但原文没这层意思。

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GWD-13-Q22:
In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars.  When, as often happens, a collar slips off, it is put back on.  Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilizer dart. 注射镇静剂后才能把雷达全重新套上  Female rhinoceroses that have been frequently recollared have significantly lower fertility rates than uncollared females.  Probably, therefore, some substance in the tranquilizer inhibits fertility.
结论：镇静剂导致低怀孕率

Which of the following is an assumption on which the argument depends?

A.        The dose of tranquilizer delivered by a tranquilizer dart is large enough to give the rangers putting collars on rhinoceroses a generous margin of safety.
B.        The fertility rate of uncollared female rhinoceroses in the park has been increasing in the past few decades.
C.        Any stress that female rhinoceroses may suffer as a result of being immobilized and handled has little or no negative effect on their fertility. 排出他因
D.        The male rhinoceroses in the wildlife park do net lose their collars as often as the park’s female rhinoceroses do.
E.        The tranquilizer used in immobilizing rhinoceroses is the same as the tranquilizer used in working with other large mammals.

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GWD-12-Q29:
The Earth’s rivers constantly carry dissolved salts into its oceans.  Clearly, therefore, by taking the resulting increase in salt levels in the oceans over the past hundred years and then determining how many centuries of such increases it would have taken the oceans to reach current salt levels from a hypothetical initial salt-free state, the maximum age of the Earth’s oceans can be accurately estimated.

Which of the following is an assumption on which the argument depends?

A.        The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.
B.        At any given time, all the Earth’s rivers have about the same salt levels.
C.        There are salts that leach into the Earth’s oceans directly from the ocean floor.
D.        There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.
E.        None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans. 没有状语
过去100年中盐增加总量 /  100年 =  每年恒定的进入海的盐量
   现在总的海中的盐量（默认初始为0） /  每年恒定的进入海的盐量（上面求得）=  海形成的最大年龄（暗示可能盐有消耗，因此是最大年龄）
   A说：过去100年中进入海中的盐量不能异常的高（暗示如果异常高的话，每年恒定的进入海的盐量这个数值就不能作为第二个等式的分母）所以是assumption
   B说：在一个特定的时间，所有的河里盐量一致——》无关，不能从原文信息中衍生
   E说：海中的盐没有被生物活动所消耗——》文章说了求的是最大年龄，因此有消耗也属于范围之内
Lawyer开始选E：
这道题已作过2个多月了，现在再回来想一想，其实理解了该题的主要词的含义和严格遵循所有推理信息来之原文，就明白为何E是正确答案，A不是。
1。必要型假设题有两类：DEFENDER（排除其他可能性，排除削弱或攻击结论成立的可能性因素）和SUPPORTER（GAP），显然该题属于DEFENER类
1。resulting increase 。由于河流的SALT流入海洋导致的盐分的增加，用这增加去计算海洋的年龄，实际就是指海洋盐分增加的速率，即每个单位年度的盐分增加量，这个单位年度可以是100年，也可以使50年，原文没说，我们不知道，反正是个速率。这个速率的最大特点是原文没告诉怎末计算出来，任何关于他如何计算出来的说法都是典型的加入自己的想象，这个最大特点是我们很难攻击它，因为不知如何算出速率，不知用那一年的数据，不知如何加权以消除偏差。等等。反正这是个最难攻击的词。只有一个原因，原文没给其它任何信息。
2。原文计算海洋最大年数的方法：current salt levels （即现在海洋的盐的浓度或水平）除以resulting increase 。因为起点是salt-free state，即零。所以，该题可攻击的因素只剩下current salt levels （即现在海洋的盐的浓度或水平），即current salt levels 是否能反映真实的现在应该有的浓度，即在该速率下，花多少年所能达到的浓度。如果如E取非所说，即有些河流流入的盐没了，则目前的salt levels 低估了，算出的年度偏小，结论不能成立。
3。A选项攻击的是速率，但是，它只能可能性的攻击它，就是说，如果用的数据恰好是不正常的数据，则能影响它，但也有可能取的数据正好。其实产生这些情况的原因在于原文没给任何有关计算速率的信息。所以它不能使结论不能成立，只能使结论可能不成立。所以不是答案。
后来他意识到E错误，应该选A：
答案应该是A。
原来的错误来之于对原文的错误理解： over the past hundred years 是指过去的一百年。如果是过去几百年，应该为over the past hundreds of years。一个hundred有加“S”，一个没有。所以原文的resulting increase 是指过去一百年的盐分增加量，而不是简单的过去某个时间段的盐度增加量。后者的理解导致了我以前的错误分析和结论。SORRY。
原文的主题意思：先算出过去一百年的盐度增加，再算出海洋从盐度为零到目前盐度需要花多少个世纪（一个世纪正好一百年）的这种增加量。
算法为：目前盐度/过去100年的盐度增加量=多少个世纪从零盐度到目前盐度。
该算法的假设：过去100年的盐度增加量可以当作速率，即每个100年的盐度增加量是一样的或低估了（因为低估，算出的时间比实际大）。
结论。这种算法可以精确算出海洋最大年龄
A。将A取非，则过去一百年的盐度增加量作为速率是高估了，则算出年龄比实际小。结论不成立。故为答案
E。取非。有些盐被消耗掉。如果消耗掉的盐发生在过去的一百年，则过去一百年的盐度增加量作为速率是低估了。这样反而支持结论，所以不是假设。如果消耗掉的盐发生在过去一百年以外，则无关。因为不在计算范围内。
再次为给我误导的朋友道歉。

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GWD-9-Q40:
Agricultural societies cannot exist without staple crops. Several food plants, such as kola and okra, are known to have been domesticated in western Africa, but they are all supplemental, not staple, foods. All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams. Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

Which of the following is an assumption on which the argument depends?

A. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.（如果西非人在引进rice和yam之前已种植未被记录的staple crops，那引进它们的时间就不能作为那里农业社会开始的时间了）
B. There are no plants native to western Africa that, if domesticated, could serve as staple food crops. 没有涉及关键问题：时间
C. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.
D. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.
E. Kola and okra were domesticated in western Africa before rice and yams were introduced there.
Answer:A
B 取非为There are some plants native to western Africa that, if domesticated, could serve as staple food crops
因为即使这样，你不知这些PLANTS domesticated是在rice and yams were introduced into western Africa 之前还是之后，如果之后，则结论仍能成立。即B取非不一定使结论不成立。而A取非是结论一定不成立

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GWD-9-Q24:
For similar cars and drivers, automobile insurance for collision damage has always cost more in Greatport than in Fairmont. Police studies, however, show that cars owned by Greatport residents are, on average, slightly less likely to be involved in a collision than cars in Fairmont. Clearly, therefore, insurance companies are making a greater profit on collision-damage insurance in Greatport than in Fairmont.
G的汽车保险费比F高
G的撞车比F少
----G的保险公司利润比F高。
Which of the following is an assumption on which the argument depends?

A. Repairing typical collision damage does not cost more in Greatport than in Fairmont.
B. There are no more motorists in Greatport than in Fairmont.
C. Greatport residents who have been in a collision are more likely to report it to their insurance company than Fairmont residents are.还是赚得多。
D. Fairmont and Greatport are the cities with the highest collision-damage insurance rates.
E. The insurance companies were already aware of the difference in the likelihood of collisions before the publication of the police reports.[A]