must

为may的否定回答：Please don’t.或No, you n’t.肯定回答为：Yes, please.或Certainly或者sure一、例句：1、May I ask you some questions?我能问你几个问题吗?Sure!当然了!2、May I go home now?现在我可以回家了吗?No, you mustn’t.　不,你千万别走。…