与现在完成时连用的时间状语如下:
“for+时间段 / since(作介词)+时间点”;eg. for three years since three years ago
since(作连词)+ 从句 (从句中的动词用过去时)。因为since引导的从句表示的是一段时间,具有延续性,所以主句中的谓语动词要用延续性动词。
eg. John has been an English teacher here since he came to our city.
Since 后面加一个时间点,就是说自从那一个时间点开始算起