it was ,i should say ,very kind of you to come all the way to help them,but you didn`t have to.为什么用“didn`t have to”?
问题描述:
it was ,i should say ,very kind of you to come all the way to help them,but you didn`t have to.
为什么用“didn`t have to”?
答
选A have to (help them)后面可省略
答
have to是必须
didn`t have to是不必要
didn`t 原句为过去式