请教LSAT-2-IV-16,21,23

joywzy · 发表于 2003-5-7 16:41:00

16. Nuclear fusion is a process whereby the nuclei of atoms are joined, or “fused,” and in which energy is released. One of the by-products of fusion is helium-4 gas. A recent fusion experiment was conducted using “heavy” water contained in a sealed flask. The flask was, in turn, contained in an air-filled chamber designed to eliminate extraneous vibration. After the experiment, a measurable amount of helium-4 gas was found in the air of the chamber. The experimenters cited this evidence in support of their conclusion that fusion ad been achieved.

Which one of the following, if true, would cast doubt on the experimenters’ conclusion?

(A) Helium-4 was not the only gas found in the experiment chamber.

(B) When fusion is achieved, it normally produces several by-products, including tritium and gamma rays.

(C) The amount of helium-4 found in the chamber’s air did not exceed the amount of elium-4 that is found in ordinary air.

(D) Helium-4 gas rapidly breaks down, forming ordinary helium gas after a few hours.

(E) Nuclear fusion reactions are characterized by the release of large amounts of heat.

答案:C,我明白这是对evidence的削弱,请问E,算不算他因削弱,提出了另一个标准呢?

23. An advertisements states:

Like Danaxil, all headache pills can stop your headache. But when you are in pain, you want relief right away. Danaxil is for you-no headache pill stops pain more quickly.

Evelyn and Jane are each suffering from a headache. Suppose Evelyn takes Danaxil and Jane takes its leading competitor.

Which one of the following can be properly concluded from the claims in the advertisement?

(A) Evelyn’s headache pain will be relieved, but Jane’s will not.

(B) Evelyn’s headache pain will be relieved more quickly than Jane’s.

(C) Evelyn’s headache will be relieved at least as quickly as Jane’s.

(D) Jane’s headache pain will be relieved at the same time as is Evelyn’s.

(E) Jane will be taking Danaxil for relief from headache pain.

答案:C,为什么C比B好吗?

21. Efficiency and redundancy are contradictory characteristics of linguistic systems: however, they can be used together to achieve usefulness and reliability in communication. If a spoken language is completely efficient, then every possible permutation of its basic language sounds can be an understandable word. However, if the human auditory system is an imperfect receptor of sounds, then it is not true that every possible permutation of a spoken language’s basic language sounds can be an understandable word.

If all of the statements above are true, which one of the following must also be true?

(A) Efficiency causes a spoken language to be useful and redundancy causes it to be reliable.

(B) Neither efficiency nor redundancy can be completely achieved in spoken language.

(C) If a spoken language were completely redundant, then it could not be useful.

(D) If the human auditory system were a perfect receptor of sounds, then every permutation of language sounds would be an understandable word.

(E) If the human auditory system is an imperfect receptor of sounds, then a spoken language cannot be completely efficient.

答案:E, 这题我还是不会做啊?怎么办呢?

谢谢.

mindfree · 发表于 2003-5-7 20:51:00

1. 在做逻辑题目时,一定要把握相关性原则. 我以前提到思路要在在原文的逻辑关系中,不能脱离原文的link. heat在此题中是无关概念, 要让heat成为有关概念, 就要填补一个gap, 就是在实验中有没有观测到heat. 如果原文提到实验中没有测试到large amount of heat, E就是有关选项并是答案. 你既然理解C是答案, 就应该明白C有关是因为原文中提到了实验中对Helium的观测结果.

2. 数学题. CD中没有人比Zeros发贴多==>其他人发帖数小于等于Zeros的发帖数. 原文的比较也是说其它头痛药不比D见效快==>其它either慢or等于D

mindfree · 发表于 2003-5-7 21:06:00

3. 我认为先用排除法. 这种题目要把思路严格地局限在原文的逻辑关系内, 当自己是个idiot.
原文中的两个IF标出了逻辑关系:
1. "a spoken language is completely efficient"(A)-->"every possible permutation of its basic language sounds can be an understandable word"(B);
2. "the human auditory system is an imperfect receptor of sounds"(C)-->"it is not true that every possible permutation of a spoken language’s basic language sounds can be an understandable word"(非B)

然后看选项:
A. 不对, 原文没有提到这两个逻辑关系
B. 不对, 原文没有提到complete redundancy可能性. 原文提到了complete efficiency, 但是并没有说它是否可能. 从原文的第二个逻辑关系看, 如果听觉系统不完善, complete efficiency才不可能, 言下之意是如果听觉系统完善(即使这个假设是错的, 原文并没有否定这个假设, 所以不违背原文的逻辑关系),就可以达到complete efficiency.
C. 不对, 原文没有提到complete redundancy
D. 不对, 此选项是第二个逻辑关系的否命题, 与原命题不等价,可对可错, 不能从原文推出来.
E. 对. C-->非B-->非A

你可以通过相关性排除前三个选项, 再根据逻辑关系找出D的错误并验证E的正确性.

joywzy · 发表于 2003-5-7 21:29:00

以下是引用mindfree在2003-5-7 20:51:00的发言：
1. 在做逻辑题目时,一定要把握相关性原则. 我以前提到思路要在在原文的逻辑关系中,不能脱离原文的link. heat在此题中是无关概念, 要让heat成为有关概念, 就要填补一个gap, 就是在实验中有没有观测到heat. 如果原文提到实验中没有测试到large amount of heat, E就是有关选项并是答案. 你既然理解C是答案, 就应该明白C有关是因为原文中提到了实验中对Helium的观测结果.

如果原文中HEAT呢？
如果原文中没有HEAT呢？原文中就是没有出现HEAT，那么E也是答案了？我真是糊涂了。

mindfree,我不大明白，他因削弱不是提出原文没有的概念吗？这不是无关啊？这点我不明白，能不能解释一下？

谢谢。

joywzy · 发表于 2003-5-7 21:32:00

2，关键是这句的理解：

no headache pill stops pain more quickly.

你理解是对的：其它药不比P 更见效。

我的理解是错的：P 比其它药更有效。

joywzy · 发表于 2003-5-7 21:52:00

第三题，用排除法丢掉原文没有的概念complete redundancy，和A。

然后再用逻辑关系推。E. 对. C-->非B-->非A，我明白了。

这个办法好。谢谢MINDFREE!!

mindfree · 发表于 2003-5-7 22:26:00

1. 所谓其它原因削弱是指用一个新的原因解释现象, 答案中一定会将新的原因和现象联系起来. 你回想一下以前所见过的题目, 新的原因不会是单独给出不和现象联系. 例如那道孵蛋的问题, 新的原因说蛋的质量随时间变化, 和孵蛋有关. 举一个假设题目中的非它因: 杜德伟吃多了,杜德伟肚子痛,所以吃多了-->肚子痛. assumption就是不是因为吃了E coli而导致了肚子痛. 如果选项只说他没吃E coli, 就不是答案, 因为没有将E coli和肚子痛联系在一起, 并且common sense也不能解释.

Heat在原文中并没有提到, 你不能确认是否观测到了heat, 所以无关.

joywzy · 发表于 2003-5-7 22:43:00

你说的这个，他因削弱须与原文有关，我不大好理解。

我找了这个做过的题目，请你看看.

LSAT-1-IV-7

7. A recent survey showed that many workers in a certain company are dissatisfied with their jobs. The survey also showed that most of the dissatisfied workers believe that they have little control over their job assignments. Therefore, to increase workers job satisfaction the company’s management need only concentrate on changing workers’ beliefs regarding the degree of control they have over their job assignments.

Which one of the following, if also shown by the survey, would most seriously call into question the conclusion made by the author of the passage?

(A) The dissatisfied workers feel that their wages are too low and working conditions are unsatisfactory.

答案：A，与原文无关啊要>

LSAR5. A government agency publishes ratings of airlines, ranking highest the airlines that have the smallest proportion of late flights. The agency’s purpose is to establish an objective measure of the relative efficiency of different airlines’ personnel in meeting published flight schedules.

Which one of the following, if true, would tend to invalidate use of the ratings for the agency’s purpose?

LSAT-2-IV-5

5. A government agency publishes ratings of airlines, ranking highest the airlines that have the smallest proportion of late flights. The agency’s purpose is to establish an objective measure of the relative efficiency of different airlines’ personnel in meeting published flight schedules.

Which one of the following, if true, would tend to invalidate use of the ratings for the agency’s purpose?

(B) Flights are often made late by bad weather conditions that affect some airlines more that others.

答案：B，这都是提出了原文没有的概念，坏天气。

又比如这题的HEAT有没有提跟这个有关吗？

为什么你说他因削弱，需要与原文的LINK有关呢？这几个都是没关的。

谢谢。

mindfree · 发表于 2003-5-7 23:31:00

我前面说过如果文中没有联系原因和现象, 并且common sense也解释不了的话, 就错. 比如我的例子中的E coli一般人不接触,不知道是什么. 7中的联系根本不用给出, 工资低加工作环境差当然导致员工不满.

5中的关系很明确:坏天气导致航班误点.如果选项只说有些地区经常会出现坏天气, 次选项就不是答案, 因为没有将天气和航班误点联系在一起.

albert · 发表于 2003-5-8 22:35:00

以下是引用mindfree在2003-5-7 20:51:00的发言：
1. 在做逻辑题目时,一定要把握相关性原则. 我以前提到思路要在在原文的逻辑关系中,不能脱离原文的link. heat在此题中是无关概念, 要让heat成为有关概念, 就要填补一个gap, 就是在实验中有没有观测到heat. 如果原文提到实验中没有测试到large amount of heat, E就是有关选项并是答案. 你既然理解C是答案, 就应该明白C有关是因为原文中提到了实验中对Helium的观测结果.

mindfree,你好。看了你的分析。挺精辟。
但是这道题目我还是有疑问。。
原文的思路是：因为那种气体是反应的副产品，所以现在出现了这种气体，说明反应成功了。（Assumption: 气体是否出现是判断反应有否成功的一个条件）
批驳的办法：
1. 否定前提，根本没有出现这种气体。。就是标准答案。
2. 否定assumption, 判断反应是否成功的唯一标准是是否产生large amount of heat，和有否出现气体无关.
所以，我觉得两个好象都对？

请教LSAT-2-IV-16,21,23

请教LSAT-2-IV-16,21,23

请教MINDFEE关于他因削弱

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