GMAT逻辑必备——GMAT逻辑总纲（三）

myice

第三节：解释。
英文标志词：explain, reason, account for, provide a rationale for, reconcile the discrepancy/paradox.
读文章方式：不要关心文章的推导过程，只需从文中拎出所要解释的对象说它对即可，用常识解题。
1．    解释结果。
例1. The population of elephant seals, reduced by hunting to perhaps a few dozen animals early in this
century, has soared under federal protection during the last few decades. However, because the
species repopulated itself through extensive inbreeding, it now exhibits a genetic uniformity that is
almost unparalleled in other species of mammals, and thus it is in far greater danger of becoming
extinct than are most other species.
  Given the information in the passage above, which of the following is most likely the reason that
other species of mammals are less likely than elephant seals to become extinct?
(A)    Other species of mammals have large populations, so the loss of a few members of the species is not significant.
(B)    Other species of mammals have increased their knowledge of dangers though the experience of generation after generation of animals.
(C)    In other species of mammals, hunters can readily distinguish between males and females or between young animals and adults.
(D)    In other species of mammals, some members of the species are genetically better equipped to withstand a disease or event that destroys other members of the species.
(E)    Other species of mammals have retained habits of caution and alertness because they have not been protected as endangered species.

myice

2．    解释矛盾。（注意侧重点）
例2. During the day in Lake Constance, the zoo-plankton D. hyalina departs for the depths where food is
scare and the water cold. D. galeata remains near the warm surface where food is abundant. Even though D. galeata grows and reprocess much faster, its population is often outnumbered by D. hyaline.
Which of the following, if true, would help resolve the apparent paradox presented above?
(A)    The number of species of zooplankton living at the lakes is twice that of species living at the surface.
(B)    redators of zooplankton, such as white-fish and perch, live and feed near the surface of the lake during the day.
(C)    In order to make the most of scare food resources, D. hyaline matures more slowly than D. galeata.
(D)    D. galeata clusters under vegetation during the hottest part of the day to avoid the sun’s rays.
(E)    D. galeata produces twice as many offspring per individual in any period of time does D. hyalina.

例3. For the United Stats meat industry, there is good news and bad news. The bad news in that over the
last three years people in the United States have been eating less meat. The good news is that during
this same time period meat producer’s profits have risen steadily.
  Which of the following, if true during the last three years, contributes most to a resolution of the
apparent discrepancy above?
(A)    eople have been eating less meat because they are more health conscious than in the past.
(B)    In the United States many new restaurants that specialize in vegetarian meals have opened.
(C)    Competition from the growing fish industry has forced meat producers to sell meat at bargain prices in an attempt to attract more consumers.
(D)    Countries that are unable to produce enough meat for their populations have become a new and lucrative market for United States meat producers.
(E)    Meat producers have invested large amount of money on advertising in order to win back consumers who have decreased their meat consumption.

myice

第四节：填空。
英文标志词：▁▁和complete the sentence。
读文章方式：不要关心文章的推导过程，只要知道文章说了什么即可，注意文章前后通过相同词的连接。
1．完成文章最后一句话。
2. 与文章前面所给信息相一致。
例. Which of the following best completes the passage below?
  “Government” does not exist as an independent entity defining policy. Instead there exists a group of
democratically elected pragmatists sensitive to the electorate, who establish policies that will result
in their own reelection. Therefore, if public policy is hostile to, say, environmental concerns, it is not
because of governmental perversity but because elected officials believe that ____.
(A)    environmentalists would be extremely difficult to satisfy with any policy, however environmentally sound
(B)    environmental concerns are being accommodated as well as public funds permit
(C)    the public is overly anxious about environmental deterioration
(D)    the majority of voters vote for certain politicians’ idiosyncratic positions on policy issues
(E)    the majority of voters do not strongly wish for a different policy

myice

第五节：句子作用题。
英文标志词：boldface, play roles.
读文章方式：首先分析黑体字部分是evidence还是conclusion，然后通过转折词判断evidence和conclusion间的关系。
例1. The use of nets at beach resorts to protect swimming areas from sharks has been criticized by
environmentalists because the nets needlessly kill thousands of marine animals annually. However, environmentalists have recently discovered that an electrified cable buried beneath the periphery of swimming areas causes sharks to swim away while harming neither humans nor marine life. Hence, by installing such cables, resort communities will be able to maintain tourism while satisfying environmentalists’ concerns.
   The statement concerning what the environmentalists recently discovered plays which of the
following roles in the argument?
(A)    A premise of the argument
(B)    The conclusion of a key term in the argument
(C)    A clarification of a key term in the argument
(D)    A reiteration of the conclusion for the sake of emphasis
(E)    A statement of the position that is being argued against


例2. 证据表明：1喝可乐的人中心肌衰退的比例超过常人。这说明：2可乐导致心肌功能衰退。所
以，3可乐不好。但就算证据正确，由于4喝可乐的人往往在喝之前已经是心力衰竭者，所
以不能说明可乐导致心功能衰退。并且5可乐中含有大量微量元素，所以6喝可乐好。7请喝可乐吧！
1、是支持中间结论2(mid conclusion)的evidence；2、是mid conclusion，支持conclusion3；3、是
conclusion， 4和5也是evidence，它们反对2和3，其实是反对1? 2?3的论证(argument,
argument=evidence+conclusion)；4、是通过指出A?B本身的错误(类似于flaw)对1?2进行削
弱，而5是通过C?B对2?3进行削弱的。4, 5均支持conclusion6的成立。7和本文的逻辑推导无关，称作suggestion，其位置一般在文章的最后。
例3. 彗星(comet)进入A星球大气层前的颗粒大小没有被观察到。但人们可以根据1comet颗粒上
含有硫磺(sulfa)来推测颗粒大小。Comet颗粒本身一定是不含sulfa的， 2A星球云层含有大量
的sulfa。Comet颗粒必须有足够的大小不被烧光而穿过大气层，才能携带上sulfa。
问题：The boldface in the argument above plays which of the following roles?
A.    Both 1 and 2 support the conclusion.
B.    1 support conclusion and 2 support 1.
答案是：A.