FeiFei-52题。

PopularKing

我认为此题的答案C有问题。如果把C中的NOT去掉不能削弱结论，反而加强。请指教。

52. Birds need so much food energy to maintain their body temperatures that some of them spend most of their time eating. But a comparison of a bird of a seed-eating species to a bird of a nectar-eating species that has the same overall energy requirement would surely show that the seed-eating bird spends more time eating than does the nectar-eating bird, since a given amount of nectar provides more energy than does the same amount of seeds
The argument relies on which one of the following questionable assumptions
(A) Birds of different species do not generally have the same overall energy requirements as each other
(B) The nectar-eating bird does not sometimes also eat seeds
(C) The time it takes for the nectar-eating bird to eat a given amount of nectar is not longer than the time it takes the seed-eating bird to eat the same amount of seeds
(D) The seed-eating bird does not have a lower body temperature than that of the nectar-eating bird
(E) The overall energy requirements of a given bird do not depend on factors such as the size of the bird, its nest-building habits; and the climate of the region in which it lives

felix2816

answer"c" doesn't have any problem.
total energy requirement=eaten food(seed or nectar)*spend time on eating

dorbear

同意Felix2816，这就是一个排除它因型假设呀！为什么一定要去反呢在去看呢，好像这里好多网友都在这么做。

即使取反，那肯定削弱了原来命题：它因存在，不是吃得多，而是吃得慢造成的时间花费差异。

PopularKing

I am still a little confused.

Is the assumption in C questionable？

This CR is looking for a questionable assumption.

seanql

nectar鸟和seed鸟需要能量一样多，但nectar食物单个能量大，所以nectar鸟吃的数量少。结论：nectar鸟吃东西花的时间少。

使以上必然成立的条件（assumption)是nectar鸟一定吃的更快，不然还是有可能花的时间比seed鸟多。和C相反，所以c questionalble.

tyghbn

there are three scenarios, same, shorter, and longer.     "Not longer" in C means "same or shorter". somewhow i am not convinced that "shorter" is the right answer. on ther other hand, I think "longer" seems to be logically reasonable. what do you guys think?

kevingu

其实我觉得这个问题根本就不用去想是不是削弱，你看文章的推理过程是

从： 吃东西的量－－－吃东西消耗的时间，这两者之间转换必然涉及一个速度de问题，

也就是assuption是关于速度的，所以只有c对

ricky663

一道好题，大家应该好好思考一下。C绝对正确

cicilla

我觉得这道题之所以会有点费解，因为C和很多assumption题目正确答案not+削弱中的削弱是给出其它原因得到相同的结果（异因同果），而这里的C是给出了其它原因，得到不同的结果（异因异果），等于同时给了它因又削弱了结论，并不是说有其它原因造成了文中的结论。

原文：原因：N能量比S高   结论：S鸟花费的时间长（因为要吃得多）

C取非: 原因：N鸟吃的时间长  结论：N鸟花费的时间有可能更长（就是S鸟花费的时间不一定更长）

这种weaken方法，好像不多见。

不知道我说得对不对啊？思路有问题的地方，请指教！（就要考了，可别出现什么重大逻辑思维问题）

cicilla

看了Lawyer_1总结得weaken的因果关系的削弱，说一种方法是切断因果，说有因无果或者有果无因。那这道题就是无因无果

不知道我想的对不对。