1 . The limits of a person’s intelligence，generally speaking，are fixed at birth，but ____________________he reaches these limits will depend on his environment.

2 . 他为什么做这件事还不十分清楚。
__________________________________ wasn’t quite clear.

3 . 我们需要的是更多的水。
____________________________ is more water.

4 . 有人担心，洪水的结束将是另一场疾病的爆发。
It is feared ______________________________ the floods, another disease would ______________.

5 . 我想不明白的是为什么他老是上课迟到。
____________ I can’t understand is _________ he is always ______________ class.

6 . 火星上有没有人类还不确定。
_______ is uncertain ______________________________ on Mars.

7 . 我想要知道的是谁解决了这个问题。
__________ I want to know is ______________________________________.