情态动词have to的否定形式
问题描述：
情态动词have to的否定形式
have to的否定形式是don't have to吧,而其他情态动词几乎都是后面直接加not,还有没有像have to这种的?
答
cf:You don't have to knock—just walk in.不必敲门 —— 进来就是了
used to
We didn't use to like him much when we were at school.以前我们同学时,我并不太喜欢他.