第2个回答 2010-10-31
since是一个从属连词，它可以引导时间状语从句‘原因状语从句和方式状语从句等，从句既可置于主句之前，亦可置于主句之后．
1．从属连词since引导时间状语从句，意谓”自从......以来”．since引导的时间状语从句有两种用法：
第一种是从句用现在完成时，从句用一般过去时，表过去某个时间开始直到现在．如：
（1）I have not laughed since I became deaf . 自从我聋了以后我就没有大笑过．
（2）It's been years since I enjoyed so much as last night . 我已经好多年没有像昨晚那样痛快了．
since经常用ever加强语气．如：
（3）We've been friends ever since we met at school . 我们自从同校相识后就一直是朋友．
第二种是主句用过去完成时，从句用一般过去时或过去完成时，表过去某个时间知道过去某个时间．如：
（4）Since she came to me , we had been happy . 自从她来到我这里，我们一直很快活．
（5) Two weeks had passed since Martin had seen him . 自从马丁见到他以后，两周已经过去了．
2．从属连词since引导原因状语从句，意谓”既然”‘”因为”‘”由于”．如：
（6）Since you are going , I will go too . 既然你要去，我也要去吧．
（7）Why do people come to his lectures since he is difficult to understand ? 既然他的话难听懂，为什么人们还要来听他的演讲呢？
（8）Aircraft noise is a particular problem here since we're close to Heathrow Airport . 由于我们*近希思罗机场，这里的飞机噪声就成了一个严重的问题．
3．since亦可用作介词．如：
（9）We hadn't seen each other since Oxford . 我们自从牛津别后就彼此没有见过面．
(10) I have not heard from him since writing last . 自上次写信以后，我没接到过他的信．
与after和before一样，since既可用作从属连词，亦可用作介词．但是这三个词后跟的-ing形式，必须看作介词和动名词组合，不能看作从属连词引导的省略分句，因为这里的-ing形式可以用物主代词修饰．如：
（11) Since my coming to London , I have not been well. 自从我来伦敦以后就一直没有好过．
4．since亦可用作副词．如：
（12) Her husband died ten years ago but she's since remarried . 她的丈夫于十年前去世，但是她后来又结婚了．
（13) He came to England three years ago and has lived here ever since . 他三年前来到英国，从那以后就一直住在这里．本回答被提问者采纳