在下列各句的空白处填入一个最恰当的单词。

1.  Cao Chong had a good way to_____ the big heavy elephant.

2.  The room is too_____ for six persons to live in.

3.  Miss Li taught us a lot of useful _____ for example, agree in with other people.

4.  Manatees are very huge.  They are about l,000 _____. 

5.  In the zoo, animals have to live in small _____. 

6.  Parents should _____ their children to behave well.

7.  There isn't enough _____ left for the cows. They'll be hungry.

8.  He is _____. He always fights with others.

9.  _____ can't grow in the desert because there is no water there.

10.  My grandfather is about sixty years old and his hair has turned _____. 

相关关系是指（）。

A．变量间的非独立关系

B．变量间的因果关系

C．变量间的函数关系

D．变量间不确定性的依存关系