1. 通常用法:
当since表示“自从”时,不管它是用作介词、连词还是副词,它都通常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。
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。
2. 非通常用法:
在以下情况下可以连用除现在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 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。
以上各句中的it is也可换成 it has been,不过在口语或非正式文体中,用一般现在时的情况比较普遍。
②当主句谓语动词为seem, appear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)
1. since 用作介词,表示时间时,谓语动词通常用现在完成时和过去完成时。如:I’ve known her since 2005. 我从2005年起就认识她了。(不能说I know her since ...)I was sorry when Jacky moved to America; we had been good friends since university days. 当杰基搬到美国去时,我很难过;大学时代以来我们就一直是好朋友。
偶尔也可以用现在时和过去时,特别是在关于变化的句子中,例如:
You’re looking much better since your operation. 手术后你看上去好多了。
She doesn’t come round to see us so much since her marriage. 自从结了婚,她就不怎么过来看我们了。
Things weren’t going so well since Father’s illness. 父亲生病以来,景况不太好。
2. It is / was ... sice ... 和It has been / had been ... since 都表示“自从...以来已经有(过去)多长时间了”,前者是英国英语用法,后者是美国英语用法。
3. since 用作连词,引导时间状语从句时,主句和从句都可以根据意思的不同,可以使用完成时,也可以用过去时。试比较:
I’ve known her since we were at school together. 自从我们一起上学的时候,我就认识她了。
I’ve known her since I’ve lived in this street. 自从我住到这条街上,我就认识她了。
You’ve frunk about ten cups of tea since you arrived. 你到了以后,已经喝了差不多十杯茶了。
You’ve drunk ten cups of tea since you’ve been sitting here. 你在这里坐下以后,已经喝了差不多十杯茶了。
We visit my parents every week since we bought the car. 我们自从买了这部汽车每周都去看望我的父母。
We visit my parents every week since we’ve had the car. 我们自从有了这部汽车每周都去看望我的父母。
【说明】此解答中的例句全部摘自《牛津英语用法指南》第四版579节。