用could, can, may, must, needn'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: But_______  finish my homework first.

    A: OK.  You_______ do it at once.