一、since通常通常搭配的时态
当since表示“自从”时,不管它是用作介词、连词还是副词,它通常都要与现在完成时连用.如：
I’ve worn glasses since my childhood.我从小就戴眼镜.
The works have been closed since January.一月份以来这些厂就关闭了.
He’s put on a lot of weight since he gave up smoking.他戒烟后体重增加了许多.
Nothing has happened since.从那以后未发生什么事.
She moved to London last May and has since got a job on a newspaper.她去年五月到伦敦此后一直在报社工作.
有时连用现在完成进行时.如：
He has been working since noon.他从中午就开始工作了.
二、since搭配时态的特殊情况
虽然since通常要与现在完成时连用,但在以下情况,它也可以连用除完成时态以外的其他时态：
1.当主句表示“多长时间”时,动词可用一般现在时（当然也可用现在完成时）.如：
It’s a long time since I met you last.好久不见了.
It’s just a week since we arrived here.我们到这里才一个星期.
It’s a long time since I met you last.从上次见到你,已有很长时间了.
以上各句的it is也可换成 it has been,不过在口语或非正式文体中,用一般现在时的情形比较普遍.
2.当主句谓语动词为seem等连系动词时.如：
It seems like years since we last met.我们似乎几年未见面了.
It seems like years since I last saw you.从上次见到你以来好像已经有许多年了.
3.当主句和从句表示情况“变化”时.如：
She doesn’t come round to see us so much since her marriage.自从结了婚,她不怎么过来看我们了.（原来经常来,结婚后就不怎么来了）
Since he went on that course he thinks he knows everything.自从他选了那门课程,他就认为自己什么都懂了.（原来不认为自己什么都懂,但选了那门课程后就认为自己什么都懂了）
