since
prep, conjunction, adv
sɪns prep, conjunction, adv
1 from a particular time or event in the past until the present, or in that period of time 自从…以来，自从…之后 generally used with a perfect tense in the main clause 通常与主句中的完成式连用
We’ve been waiting here since two o’clock.
我们从两点钟开始就在这里等了。
I haven’t played rugby since I left university.
我大学毕业后就没打过橄榄球。
She left London ten years ago, and I haven’t seen her since.
她 10 年前离开伦敦，此后我再也没有见过她。
The factory has been here since the 1970s.
这家工厂从 20 世纪 70 年代起就在这里了。
It was exactly five years since her father had died.
她父亲去世到现在正好满 5 年。
Since the end of the war over five thousand prisoners have been released.
战争结束以来，有 5000 多名战俘获释。
He lost his job five years ago, but has since found other work.
他 5 年前失去工作，但此后找到了其他工作。
I left school in 1995, and since then I’ve lived in London.
我 1995 年离开学校，此后我就在伦敦生活。
ever since (all the time since) 自从，从此
We’ve been friends ever since we were at school together.
我们从上学的时候起就一直是朋友。
She’s been terrified of the sound of aircraft ever since the crash.
自从那次飞机失事后，她就一直害怕听到飞机声。
We came to the UK in 1974 and have lived here ever since.
我们 1974 年来到英国，此后就一直在这里生活。
2 used to give the reason for something 因为，既然
Since you are unable to answer, perhaps we should ask someone else.
既然你回答不了，也许我们该问问别人了。
3
since when?
used in questions to show that you are very surprised or angry [口] 从什么时候起？〔用于问句，表示十分惊讶或气愤〕 spoken
Since when have you been interested in my feelings?
你从什么时候起开始关心我的感受了？
4
long since
if something has long since happened, it happened a long time ago 很久以前，早已…
I’ve long since forgiven her for what she did.
我早已原谅她的所作所为了。
5
since
Use to say that something started at a point in time in the past, and is still continuing. since 表示某事于过去某一时间开始，并且现在仍在继续
He has been living in Leeds since 1998.
他从 1998 年起就住在利兹。
We’ve known about it since May.
我们从 5 月份起就知道这件事了。
6
Since
is usually followed by a time expression (‘last year’, ‘this morning’, ‘4 o’clock’ etc) or by the simple past tense. Use the present perfect or the past perfect in the other clause. since 后面常跟表示时间的短语（如 last year，this morning，4 o’clock 等），或是跟一般过去式。 在另一个从句中要用现在完成式或过去完成式
I have loved movies since I first went to the cinema.
我第一次去电影院后就喜欢上了电影。
He had been seriously ill since Christmas.
他从圣诞节开始就一直病得很重。
7
it is since it has been since
Speakers of British English usually say a long time/two weeks etc …, and speakers of American English it has beena long time/two weeks etc since…, but both uses are correct. 英国英语一般说 it is a long time/two weeks etc since …，而美国英语一般则说 it has been a long time/two weeks etc since …，但两种说法都是正确的 BrE AmE
8
for
Use when you state the length of time that something has been happening. for 表示某事发生的时间长度
We have known each other for ten years (NOT 不说 since ten years) .
我们认识已经有十年了。
I had been waiting for hours (NOT 不说 since hours) .
我已经等了好几个小时了。
I haven’t seen him for ages (NOT 不说 since ages) .
我已经很久没见他了。
9
During over
and are used when you state the period of time in which something happens or changes. during 和 over 表示某事发生或变化的一段时间
During her first year at college, she had several boyfriends.
她读大学的第一年有过好几个男朋友。
Over the last six months, crime has doubled.
过去的六个月中，犯罪活动翻了一番。