英语语法详解：时间状语从句（两大条）

英语语法详解：时间状语从句
 
■引导时间状语从句的从属连词
引导时间状语从句的从属连词很多，如较基本的有before, after, when, while, as, since, till, until, as soon as 等：
Things were different when I was a child. 我小时候情况与现在不同。www.34en.com
We must strike while the iron is hot. 我们要趁热打铁。
It’s a long time since I met you last. 从上次见到你，已有很长时间了。
He waited until she was about to leave. 他等着一直到她准备离开。
除以上基本的引导时间状语从句的从属连词外，还有些本来不是从属连词却可用作从属连词的词：
(1) 表示“一…就”的从属连词：the moment, the minute, the second, the instant, immediately, directly, instantly, once, no sooner…than, hardly…when等。如：
Immediately he came I told him the news. 他一来我就把消息告诉了他。
The moment I saw him I knew there was no hope. 我一看到他就知道没希望了。
We had no sooner set out than it began to rain. 我们刚出发就下雨了。
Once he arrives, we can start. 他一来我们就可以开始。
(2) 涉及time的几个从属连词：every time(每次)，each time(每次)，(the) next time(下次)，any time(随时)，the last time(上次)，the first time(第一次)。如：
Every time I see her I’ll think of it. 每次我看到她，我就想起这事。
He felt nervous each time she spoke to him. 每次她和他讲话，他都感到紧张。
He didn’t tell me the last time I saw him. 我上次见到他时他没告诉我。
 
■与时间状语从句有关的时态问题
关于这个问题有两点值得注意：
(1) 当主句为将来时态或具有将来意义时，时间状语从句通常要用一般现在时表示将来意义，而不能直接使用将来时态：
Turn off the lights before you leave. 走前关灯。
I will tell him as soon as he arrives. 他一来我就告诉他。
(2) 与since 从句搭配的主句的时态通常是现在完成时态：
He has lived here since 1999. 自1999年以来，他就一直住在这儿。
Where have you been since I last saw you? 自我上次见到你之后你到哪里去了?
【注】在特定的语言环境中有时也可能用过去完成时或一般现在时：
It seems like years since we last met. 我们似乎几年未见面了。
Yesterday he told me that he hadn’t eaten anything since Tuesday. 他昨天告诉我自星期二以来他一直未吃任何东西。