三道LSAT题求助！

lala

11.“If the forest continues to disappear at its present pace, the koala will approach extinction,” said the biologist.
“So all that is needed to save the koala is to stop deforestation,” said the politician.
Which one of the following statements is consistent with the biologist’s claim but not with the politician’s claim?
(A) Deforestation continues and the koala becomes extinct.
(B) Deforestation is stopped and the koala becomes extinct.
(C) Reforestation begins and the koala survives.
(D) Deforestation is slowed and the koala survives.
(E) Deforestation is slowed and the koala approaches extinction.

5. All German philosphers, except for Marx, are idealists.
from which of the following can the statement above be most properly inferred?
A. Except for Marx, if someone is an idealist philosopher, then he or she is German.
B. Marx is the only non-German philosopher who is an idealist.
C. If a German is an idealist, then he or she is a philosopher, as long as he or she is not Marx.
D. Marx is not an idealist German philosopher.
E. Aside from the philosopher Marx, if someone is a German, then he or she is an idealist.

23. Teachers are effective only when they help their students become independent learners. Yet not until teachers have the power to make decisions in their own classrooms can they enable their students to make their own decisions. Students' capability to make their own decisions is essential to their becoming independent learners. Therefore, if teachers are to be effective, they must have the power to make decisions in their own classrooms.
According to the argument, each of the following could be true of teachers who have enabled their students to make their own decisions EXCEPT:
(A) Their students have not become independent learners.
(B) They are not effective teachers.
(C) They are effective teachers.
(D) They have the power to make decisions in their own classrooms.
(E) They do not have the power to make decisions

答案是B，E，E，为什么不是其它选项？是如何从题干中推出来的？

tongxun

11.“If the forest continues to disappear at its present pace, the koala will approach extinction,” said the biologist.
“So all that is needed to save the koala is to stop deforestation,” said the politician.
Which one of the following statements is consistent with the biologist’s claim but not with the politician’s claim?
(A) Deforestation continues and the koala becomes extinct.
(B) Deforestation is stopped and the koala becomes extinct.
(C) Reforestation begins and the koala survives.
(D) Deforestation is slowed and the koala survives.
(E) Deforestation is slowed and the koala approaches extinction
---------------------
这题答案最搞的是B与E，说实话：我看完题目觉得没一个完全象，就B、E好点。因为题目问的是与学家一致，而与政治家不一致。A、D与政治家一致，C两者都没说，所以无关。后来再看题目觉得两人最大的不同在于：非0速度--0速度，由此得出E与学家不一致，才胆战心惊地选了B。最后发现你的帖子后面原来有答案。早知道先看答案了，哈哈哈。
以上是我的整个思维过程。

tongxun

5、我认为是D吧。E的面太广了，把所有德国人都说成哲学家。
23、推理的线路：1老师权威----2学生自主---3自立学生---4老师有效。
问题问的是：enabled their students to make their own decisions EXCEPT:
(A) Their students have not become independent learners.
make their own decisions is“ essential to ”their becoming independent learners.没有自主，肯定没有自立，但没有自立不等于没有自主。因此，有可能自主。
(B) They are not effective teachers.
由A的解释可以看出，排除点还是自主与自立的关系，但有效与自主是互相的。也就是说，老师有效，肯定学生自主；但自立只是自主的一个基本条件而已，还有其它因素，或许是他因引起，所以不能说学生没培养起自主吧。
(C) They are effective teachers.
肯定行
(D) They have the power to make decisions in their own classrooms.
即有可能帮学生培养自主。
(E) They do not have the power to make decisions
题目中的：not until teachers have the power to make decisions in their own classrooms can ，把1-2给断开了。
说的有点乱，不明白再问。

lala

Tongxun，看了您的解释，我有了一些启发。但还有一些不明，让我们再讨论讨论。

题目要求下面陈述与生物学家一致，与政治家不一致。政治家说stop deforestation是save the koala的必要条件，即save the koala-àstop deforestation。而生物学家说森林以现在的速度消失是koala灭绝的充分条件，即森林以现在的速度消失àkoala灭绝。AE与政治家一致(因为Deforestation continue/slow 都与政治家的stop deforestation 不一致，从而推出koala extinction)。C无关。BD选项且不考虑是否与政治家相一致，B首先与生物学家不一致：生物学家是A推B，而B选项却是A非与B并存。而且B也不与政治家一致：政治家是又一个A推B，而B选项是B与A非并存。相反D符合要求。您看呢？？？

第二题，我把题目关系搞反了。题目问的是，从哪一个选项可以抽象出题目的结论？而不是从题目中可以得到哪个选项的结论。

[此贴子已经被作者于2002-6-9 14:23:41编辑过]

tongxun

lala：你的推理我都快看晕了，太复杂了。不过，能在最短的时间将题目做出的方法就是好方法！千万别管什么充分、必要，若你对逻辑精通还行，若不是，千万别信陈响动所写的那一套。通过做题、感觉，只有培养起良好的逻辑感觉才是我们目前冲击ETS的最锐利的武器！

oncemore

11. 学家说的是：只要A成立，则B成立。          A：deforestation B:extinction
    政治家理解成：只要A不成立，则B也不成立。
    其实政治家的话是学家的否命题。这题应该是考察如何削弱政治家的推理
    因此要找到正确的答案只要找到A不成立，B成立即可。显然B最合适
5.  由选项推题干，只有E才可以推出所有德国哲学家都是理想注意者

tongxun

终于来了一位逻辑科班出身的牛人。LALA， 我的逻辑全是在做题的基础上培养起来的感觉。
欢迎oncemore常来。

oncemore

我也在做LSAT，希望和大家一起交流。很多地方想不通啊！

celeste

repost it (it is from the coolaw)

11. 这个题记得以前有人在论坛上问过。问题是要求找一句话，既符合生态学家的陈述，而反过来，又与政客的观点不同。这个题目有一个办法，就是先找与政客不同的陈述。政客说，只要我们阻止滥伐，考拉就不会灭绝。而（B）说，滥伐停止了，而考拉依然灭绝了。恰恰反对了政客的观点，就是正确答案。其他几个选择运用普通逻辑的方法予以排除。D is incorrect. Even the issue of speed of deforestation was metioned, if any, by the biologist (at its present pace), it has never been touched by our politician. How can you refute someone by a point he never made?

If we go further, we can see D actually goes way around to support the claim of the politician in some way. The politician said, we only need to stop deforestation to stop the extinction. If the coala does survives because of the slowing of deforestation, what would hepen if we totally stop deforestation? I think people would expect the coala would survive too. So, D at least can not be the best answer.

The basic way to tackle this question is formal logic. The biologist's claim can be rephrased as; -stop --> die. The politician's claim can be rephrased as: stop --> -die. What they are talking are not the same things. Apparently, the politician wrongly interpreted the biologist's point. If you want to refute the claim stop-->not die, the best way is, even though deforestation stops, the coala still died, which is exactly what B says.

primefang

如果deforestration 是 A， Extinct 是B， 学者的论断是 A推B
但选项B 的解释是  否A 推 B， 这如何consistent ?