Since引导的从句一般要用什么时态

一般过去时.
1) since +过去一个时间点 (如具体的年、月、日期、钟点、1980, last month, half past six).
I have been here since 1989.
2) since +一段时间+ ago
I have been here since five months ago.
3) since +从句
Great changes have taken place since you left.
Considerable time has elapsed since we have been here.
4) It is +一段时间+ since从句
It is two years since I became a postgraduate student.

since引导的主句和从句各用什么时态？
1. since引导时间状语从句时，从句动词通常用一般过去时，主句动词用现在完成时。
We have been good friends since we met in 1980.
2.since从句中，有时也用动词的现在完成时情况，但从句意义就起了变化。
I haven't gone shopping since I was ill.
I haven't gone shopping since i have been ill.
3在It is+时间+since…这样的节后中，也可用现在完成时。

for引导的时间和since引导的时间要用什么时态?
since 常用于现在完成时或过去完成时
It's been ten years since they married.
for不能引导时间状语从句,它用来引导原因状语从句.可以用过去时
I am sorry for what I said to you.

如果是自从……（到现在），一般主句用现在完成时；
如果是“既然”，那就得看意思来决定了。

大多是现在完成时。如果是since主句就是一般过去时

现在完成时居多，望采纳

过去