can(能,会), may(可以,可能,也许), must(必须,一定,应该) have to(必须,不得不)
1. 肯定句结构:主语+can/may/must+动词原形+其它,例如:
I must go now.
2. 否定句结构: 在can/may/must后加not,例如:
You mustn’t talk aloud in the library.
3. 一般疑问句结构: 把can/may/must提在主语前,例如:
Must you go now? (Yes, I must. No, I needn’t.)
May I open the window? (Yes, you may. No, you needn’t.)
