Q40:

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 damaged, for example by a stroke, linguistic capabilities are impaired in some way.  Therefore, 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?

1. No part of a person’s brain that is damaged by a stroke ever recovers.
2. Impairment of linguistic capabilities does not occur in people who have not suffered any damage to any language center of the brain.
3. Strokes tend to impair linguistic capabilities more severely than does any other cause of damage to language centers in the brain.
4. 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.
5. 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 thebrain

答案是d，没懂~~~

题目：大部分人左脑是控制语言能力，但少数人在右边。如果脑的控制语

言部分被伤害了，语言能力就会下降。因此，如果一个人的左脑受了伤害但是语

言能力没下降，那么他一定是右脑控制语言。

问架设。

D：如果语言中心在左脑的话，任何对左脑的伤害都会对它有所损坏。

正好架桥梁。

呵呵。

不好意思，，，还想问一点，

  D ...." at least one of them."中的them指的是什么？

thanks !!!!!!!!