以下是用may, can, must提问的问句及其肯定和否定回答的示例：
1. May I go out now?
肯定回答：Yes, you may.
否定回答：No, you may not.
2. Can I use your phone?
肯定回答：Yes, you can.
否定回答：No, you can't.
3. Must I finish this report today?
肯定回答：Yes, you must.
否定回答：No, you don't have to. 或 No, you mustn't. (在某些情况下，也可以使用否定回答“you needn't”或“you don't need to”)
请注意，在某些语境中，否定回答可能会根据具体情况有所不同。
