since 是什么意思?谢谢.

副词 ad.(常用于现在完成时或过去完成时)
1.
此后;从那时到现在
She left school three years ago and has worked as a nurse ever since.
她三年前毕业,从那时起便一直当护士.
2.
之前,以前
介词 prep.
1.
(常用于现在完成时或过去完成时)自...以来,从...至今
I haven't heard from him since last year.
我自去年以来未曾收到过他的信.
连接词 conj.
1.
(常用于现在完成时或过去完成时)自...以来,从...至今
It's been ten years since they married.
他们结婚到现在已经十年了.
She has been living a hard life since her husband died.
她自从丈夫死后,一直过着艰苦的生活.
2.
既然;因为,由于
He must have taken the book since it isn't here.
他一定是把书拿走了,因为书已不在这里了.
Since it is so hot,let's go swimming.
既然天气这么热,我们去游泳吧.
以下结果来自互联网网络释义
1.
自...以后,自...以来.
中考英语介词知识点精讲大全 - 初中英语 ...
since 自...以后,自...以来.
2.
因为
职称英语理工类补全短文的解题技巧 中国招生...
since因为
3.
过去的一点时间
各种介词的用法一览-英语,中学英语,小学英...
since +过去的一点时间