问题描述：
since后加现在完成时和一般过去时的区别
比如
It's three years since he has worked there.和
It's three years since he worked there.有什么区别
比如
It's three years since he has worked there.和
It's three years since he worked there.有什么区别
问题解答：
我来补答展开全文阅读