202.Gortland has long been narrowly self-sufficient in both grain and meat. However, as per capita income in Gortland has risen toward the world average, per capita consumption of meat has also risen toward the world average, and it takes several pounds of grain to produce one pound of meat. Therefore, since per capita income continues to rise, whereas domestic grain production will not increase, Gortland will soon have to import either grain or meat or both.

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

(A) The total acreage devoted to grain production in Gortland will not decrease substantially.

(B) The population of Gortland has remained relatively constant during the country’s years of growing prosperity.

(C) The per capita consumption of meat in Gortland is roughly the same across all income levels.

(D) In Gortland, neither meat nor grain is subject to government price controls. E

(E) People in Gortland who increase their consumption of meat will not radically decrea se their consumption of grain.

GMAC的逻辑题不是数学题，不要求一定要具备充分的必要性，才能得出答案。

此题是典型的排出他因的NOT+削弱结构

现象：Gortland肉和粮食自给自足

论据：因为收入增加------所以肉的消费增加

条件：若干磅粮食----产生1磅肉

结论：因为收入增加，粮食没有增长-----所以要进口

这里，找不到明显的GAP，要想假设必须引入他因，将它否定，在题目里，可以发现有三个变量，收入、粮食、肉

考场上实在没有时间分析三者的关系，所以，只需要判断正确选项一定和这三个变量有关即可

于是可以通过排除对比，包括句型的对比，比如优先找出长的、有否定词或否定意味的、句式比较突出的选项

那么选项E，will not radically decrease 是极其符合GMAC思路的口吻，而且E说粮食的消费不会减少，正是排除他因的标准选项，这样就可以毫不犹豫地选择它。

谢谢指教，很有收获。我看到很多NN们都说assumption是模式最固定，比较好掌握的一个题型，可是我在assumption上却总也找不到感觉。也看了一些大家对排出他因和gap的分类（题目的划分），却发现有的甚至和og的解释不一样，感觉很困惑...有的题目有人列为他因，有人列为gap...

例如

8. To prevent some conflicts of interest, Congress could prohibit high-level government officials from accepting positions as lobbyists for three years after such officials leave government service. One such official concluded, however, that such a prohibition would be unfortunate because it would prevent high-level government officials from earning a livelihood for three years.

The official’s conclusion logically depends on which of the following assumptions?

A. Laws should not restrict the behavior of former government officials.

B. Lobbyists are typically people who have previously been high-level government officials.

C. Low-level government officials do not often become lobbyists when they leave government service.

D. High-level government officials who leave government service are capable of earning a livelihood only as lobbyists. D

E. High-level government officials who leave government service are currently permitted to act as lobbyists for only three years.

还有有的题目不知道是他因还是gap，如

76. A famous singer recently won a lawsuit against an advertising firm for using another singer in a commercial to evoke the famous singer’s well-known rendition of a certain song. As a result of the lawsuit, advertising firms will stop using imitators in commercials. Therefore, advertising costs will rise, since famous singers’ services cost more than those of their imitators.

The conclusion above is based on which of the following assumptions?

(A) Most people are unable to distinguish a famous singer’s rendition of a song from a good imitator’s rendition of the same song.

(B) Commercials using famous singers are usually more effective than commercials using imitators of famous singers.

(C) The original versions of some well-known songs are unavailable for use in commercials.

(D) Advertising firms will continue to use imitators to mimic the physical mannerisms of famous singers. E

(E) The advertising industry will use well-known renditions of songs in commercials.

再次请教，不胜感激.....

8. To prevent some conflicts of interest, Congress could prohibit high-level government officials from accepting positions as lobbyists for three years after such officials leave government service. One such official concluded, however, that such a prohibition would be unfortunate because it would prevent high-level government officials from earning a livelihood for three years.

咱们不看选项，

逻辑简图：

结论很简单：国会禁止高官从事某职位-------是不幸的

原因：高官会没饭吃的

这里明显有GAP，国会禁止----高官会没饭吃，为什么呀？凭什么呀？

所以需要一个假设：高官只会吃游说那口饭

咱们不看选项，

逻辑简图：

结论很简单：国会禁止高官从事某职位-------是不幸的

原因：高官会没饭吃的

这里明显有GAP，国会禁止----高官会没饭吃，为什么呀？凭什么呀？

所以需要一个假设：高官只会吃游说那口饭

76. A famous singer recently won a lawsuit against an advertising firm for using another singer in a commercial to evoke the famous singer’s well-known rendition of a certain song. As a result of the lawsuit, advertising firms will stop using imitators in commercials. Therefore, advertising costs will rise, since famous singers’ services cost more than those of their imitators.

又是一个假设;

著名歌手赢了诉讼------所以公司要停止（某首歌）的模仿

结论：因为著名歌手费用高-------所以广告费用高     为什么？不用著名歌手不行吗?

这其实就是找出他因，将它排除，公司必须得用这著名歌手

又是一个假设;

著名歌手赢了诉讼------所以公司要停止（某首歌）的模仿

结论：因为著名歌手费用高-------所以广告费用高     为什么？不用著名歌手不行吗?

这其实就是找出他因，将它排除，公司必须得用这著名歌手

看了您的分析，我就会有些明白，但是一到自己做的时候，很多地方就又很糊涂。我个人认为，反复分类做og是个解决的办法，不知道您认为如何？或者还有什么更好的建议？谢谢