题目内容：

I. 根据句意用适当的介词填空。

1.I rang the bell, but nobody replied ___________ me.

2.I felt too sorry ___________ what I had done.

3.She wrote some letters ___________ her friends, but got no from them.

4.They kept thinking ____________ the problem all the time.

5.What’s wrong __________ you? Can you tell me?