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.
