据句意及单词首字母完成句子。

1. He is h       , so he will pass the exam.

2. Students are s         to keep the classroom clean.

3. She didn't r            home until 11:00. 

4. L        , he found his book that he had lost.

5. To my s           , Tom did come to the party.

适宜于观察减压神经对心脏影响试验的动物是（）。

A.小鼠

B.大鼠

C.豚鼠

D.兔