don't have to,musn't,didin't的区别

能否解释一下musn't,needn't ,don't have to,can't ,couldn't的区别? musn‘t和 don't 的用法 can`t 和musn`t的区别 请教几个英语知识1.mustn't musn't to haven't to don't have to 2.pass和 couldn't don't have to needn't的区别 don"t need和don't have to 的区别? need t和don t have to的区别 用can,must,musn't,have to,has to填空 I didin't have to ride the bus didn't have to 和don''t have to 区别 英语语法don't have to 与 don't need to的区别和用法don't need to和 needn' needn't needn't have done 和don't need to 的区别