【英语语法】情态动词 must , mustn't , 和don't need to do 的用法
- must 必须做某事 ,
- musn't 不必须做某事，
- don't need to (过去式）不必须做某事
例句：
You don't need to go. You can stay here if you want.
It's fantastic film. You must see it.
It's lisa birthday next week . I mustn't forget to buy her a present.
