[求助]逻辑题向大家请教，谢谢。

bob

80. Advertisement: Clark brand-name parts are made for cars manufactured in this country. They satisfy all of our government automotive tests-the toughest such tests in the world. With foreign-made parts, you never know which might be reliable and which are cheap look-alikes that are poorly constructed and liable to cost you hundreds of dollars in repairs. Therefore, be smart and insist on brand-name parts by Clark for your car.
The argument requires the assumption that
(A) Clark parts are available only in this country
(B) foreign-made arts are not suitable for cars manufactured in this country
(C) no foreign-made parts satisfy our government standards
(D) parts that satisfy or government standards are not as poorly constructed as cheap foreign made parts
(E) if parts are made for cars manufactured in our country, they are not poorly constructed
答案是D，我选了C。


89. Rhizobium bacteria living in the roots of bean plants or other legumes produce fixed nitrogen, which is one of the essential plant nutrients and which for non-legume crops, such as wheat, normally must be supplied by applications of nitrogen-based fertilizer. So if biotechnology succeeds in producing wheat strains whose roots will play host to Rhizobium bacteria, the need for artificial fertilizers will be reduced.
The argument above makes which one of the following assumptions?
(A) Biotechnology should be directed toward producing plants that do not require artificial fertilize.
(B) Fixed nitrogen is currently the only soil nutrient that must be supplied by artificial fertilizer for growing wheat crops.
(C) There are no naturally occurring strains of wheat or other grasses that have Rhizobium bacteria living in their roots.
(D) Legumes are currently the only corps that produce their own supply of fixed nitrogen.
(E) Rhizobium bacteria living in the roots of wheat would produce fixed
nitrogen.
答案是E，我选了C。


91. Leachate is a solution, frequently highly contaminated, that develops when water permeates a landifill’s site. If and only if the landfill’s capacity to hold liquids is exceeded does the leachate escape into the environment, generally in unpredictable queantities. A method must be found for disposing of leachate. Most landfill leachate is sent directly to sewage treatment plants, but not all sewage plants are capable of handling the highly contaminated water.
Which one of the following can be inferred from the passage?
(A) The ability to predict the volume of escaping landfill leachate would help solve the disposal problem.
(B) If any water permeates a landfill, leachate will escape into the environment.
(C) No sewage treatment plants are capable of handling leachate.
(D) Some landfill leachate is sent to sewage treatment plants that are incapable of handling it.
(E) If leachate does not escape from a landfill into the environment, then the landfill’s capacity to hold liquids has not been exceeded.
答案是E，我想问，D为什么不对？


97. A scientific theory is a good theory if it satisfies two requirements: it must accurately describe a large class of observations in terms of a model that is simple enough to contain only a few elements, and it must make definite predictions about the results of future observations. For example, Aristotle’s cosmological theory, which claimed that everything was made out of four elements---earth, air, fire, and water---satisfied the first requirement, but it did not make any definite predictions. Thus, Aristotle’s cosmological theory was not a good theory.
If all the statements in the passage are true, each of the following must also be true EXCEPT:
(A) Prediction about the results of future observations must be made by any good scientific theory
(B) Observation of physical phenomena was not a major concern in Aristotle’s cosmological theory.
(C) For elements can be the basis of a scientific model that is simple enough to meet the simplicity criterion of a good theory.
(D) A scientific model that contains many elements is not a good theory.
(E) Aristotle’s cosmological theory described a large class of observations in terms of only four elements.
答案是B，我选了A。
我觉得A中是把必要条件和充分条件搞混了。
请指教，谢谢。

回家过年

80. 这题不算难。答案D属于假设题里的强调或加强前提或原因，是隐含假设一个必要条件。而C答案确不是一个必要条件，因为最后THEREFORE强调的是CLARK. 所以D好。

89. 是个老题。和80一样，应该注意假设题答案的必要性。而且选C有点离谱。不是假设题答案一定要有NOT的吧，而且C有削弱的意思，并且naturally更有问题。

91. D答案说的是一个结论，可是最后一句话并不能肯定推出这个结论。most landfill leachats 不一定别送到plants that are not capable of handling the highly contaminated water, 虽然从字面上看可能。有时INFER题答案就是一个隐含的假设，要满足必要性。E就是个逆否命题。

97. 这题两个必要条件A,B。但是反过来看，任何一个A或B单独都不是必要条件了，这样原来的good scientific theory 成了他们单独成立的必要条件了。而且这题B答案很明显，明显是个无关答案。

有的LSAT比这几题难度要大很多，阿门！
[em11]

Louisa_xy

楼上的MM牛啊！

bob

回家过年，非常感谢，果然牛。
关于97题，我还有问题。我们从文章可以知道，“包含很少的元素”和“对未来观察的预测”可以推出理论是好理论。那么，如果只满足一个条件，比如只有“对未来观察的预测”，这个理论就不是好的理论。可见，“对未来观察的预测”也可以由不好的理论得出来，那么这就跟选项A中的说法相背离了。A说“对未来观察的预测”一定是由好理论得出的。请指教，谢谢。

回家过年

注意A的后面的any,我觉得应该这么翻译：Prediction about the results of future observations must be made by any good scientific theory. : must 后面的是个必要条件：由任何好的科学理论的一定能MADE＝＝>predication 。你的理解有问题。
必要条件是：没有这个条件，结论一定不对。而must又是一个必要条件的关键词。

我不牛，别让牛人们见笑了。

bob

回家过年,谢谢。
我同意MUST后面是一个必要条件，但问题在于，我觉得好理论并不是“对未来观察的预测”的必要条件，因为即使是坏理论，也可以满足“对未来观察的预测”，（见我上面的回帖）。
请指教，谢谢。

回家过年

仔细看了一下, A scientific theory is a good theory if it satisfies two requirements说的到底谁是充分,谁是必要? 是不是会是这样: if A, then B 中 A 是充分条件. 可是这题又有 two requirements. 最后结论: both requirements一起是充要条件. 单独一个条件是A scientific theory is a good theory 的必要条件.
A选项Prediction about the results of future observations must be made by any good scientific theory 由任何good scientific theory 都肯定有对将来的研究的预测.
而不是你说的“对未来观察的预测" 是不是肯定由好理论得出, 这次希望你能明白.

bob

非常感谢。