用could, can, may, must, need't 填空。

1. A: ____ you answer the question in English?

    B: Sorry, I ____ ____  I answer it in English? 

    A: No, you ____. You ____ answer it in Chinese.

2. A: ____ I  ask a question?

    B: Yes, you ____. But you ____ wait a minute.

3. A: ____ I use your eraser, Bill?

    B: Sorry, I don't have one. Ask Mary. She ____ have one.

4. A: ____ you help me do the shopping?

    B: OK. Sure.

5. A: ____ you sweep the floor?

    B: Yes. But I ____  finish my homework first.