一道逻辑题~~~求助求助！！

nicholas81

For most people, the left half of the brain controls inguistic capabilities. However, some people have their language centers in the right half. When a language center of the brains is impaired, for example, by a stroke, linguistic capabilities are damaged in some way. So, 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?
B impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain
D if there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.
答案是B 不理解~为什么不是D啊~

susielei

貌似这题答案是D而不是B啊。楼主可以看下面帖子的分析：
http://forum.chasedream.com/GMAT_CR/thread-252193-1-5.html

keithyang926

好像B取非了结论也成立。
个人感觉D也是正确的。

nicholas81

知道啦~ 谢谢两位啦~~

pinkking

这题选D

5453

一些感想~~

A.    No part of a person’s brain that is damaged by a stroke never recovers 无关
B.    Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.  取非：损伤发生在哪些没有遭受任何语言区damage的人。  无关，讨论的是damage语言区。
C.    Strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.    此题只讨论了stoke，无关其他damage原因
D.    If there are language centers on the left side of the brain, any serious stroke affecting that side of the brain damages at least one of them.  取非：如果语言区在左脑，任何的storke不会damage at least one of them（左脑语言区）. 即是说如果语言区被stroke，center没被破坏，还能talk.说明语言区还是在左脑，不是在右脑。 ---语言区在左脑，任何stroke会damage语言区。言下之意，如果语言区在右脑，damage左脑是不会影响在右脑的语言区的。  
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.  如果两边都没受伤，不可能知道哪边是语言区。  无关。