for most people, the left half of the brain controls linguistic capabilities, but some people have their language centers in the right half. when a language center of the brain is damanged, for example by a stroke, linguistic capabilities are impaired in some way,. there fore, people who have suffered a serious stroke on the left side of the brain without suffering any such impairment must have their language centers in the right half.

which of the following is an assumption on which the reasoning in the argument above depends?

a. no part of a person's brain that is damaged by a stroke ever recovers.

b impairment of liguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.

c.strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.

d. if there are language centers on the left side of the brain, any serious stroke affecting side of the brain damages at least one of them.

e. it is impossible to determine which side of the brain contains a person's language centers if the person has not suffered damage to either side of the brain.

Ans: D

题目一开始给出了两个条件：1 有些人的语言中心在右脑，2 语言中心如果损坏，必然损坏语言能力。注意在给出的条件中有一个A推B：语言中心损坏（A）--> 语言能力损坏（B）。

然后题目给出了结论：如果左脑损坏但语言能力未损坏，那么语言中心必然在右脑。这个结论可以转化为：（假如语言中心在左脑），左脑损坏（A）--> 语言能力损坏（B）。

现在你可以看到了，两个A推出B中，A是不一样的（左脑损坏不等于语言中心损坏）。假设就是要在这两个A中间架桥，使得这两个A一致。所以答案必然是：脑的损坏必然导致语言中心的损坏。这样两个A就一致了。所以选D。