since前后状态的用法

首先,“since”表示“自从…起,直到现在”,”since”后面一般用过去式句子或单词,词组,前面用完成时态：
I’ve never been to a movie since I came to Guangzhou.
我自从到了广州,就没去看过一场电影.
I’ve been teaching English since I graduated from college.
我自从大学毕业后,一直教英语.
We’ve been very close since we met each other 2 years ago.
我们自从两年前认识后,一直是很要好的朋友.
She hasn’t worked since her marriage.
她结婚后,未曾去工作过.
Ever since 表示从那时到现在,此后一直：
He went to London in 1979,and has lived there ever since.
他1979年去了伦敦,从此之后,一直住在那.
“since”的第二种用法,表示原因,“由于,因为,鉴于”,用在稍正式的场合：
The hiking is cancelled since it’s raining cats and dogs.
徒步旅行被取消了,因为下着倾盆大雨.
Since we have no money,we can’t afford it for the time being.
我们没钱,所以暂时买不起.
I can’t go to your class since I am ill.
我不能去上你的课,因为我病了.
“for”也可以引导原因,用在稍口语化的场合：
I can’t let you do it for it’s gonna damage your reputation.
我不能让你这么做,因为这会毁了你的名声.
They call for a meeting for there’s something urgent to discuss right now.
他们要求立即开一个会议,因为发生了紧急的事需要讨论.