内容正文:
第十三讲 时间状语从句
一、时间状语从句的种类
1.用 when 引导:when 表示“当......时候”。
如:Things were different when I was a child. 我小时候情况与现在不同。
People breathe more slowly when they are asleep. 人睡觉时呼吸比较缓慢。
2.用 while 引导:while 表示“当......时候”。
如:We must strike while the iron is hot. 我们要趁热打铁。
I went swimming while the others played tennis. 我去游泳,其余的人都打网球去了。
注意:while 所引导的时间状语从句中谓语动词必须是持续性的,不能是短暂性的。
3.用 as 引导:as 表示“当......时候”,“随着”。
如:He dropped the glass as he stood up. 他站起来时,把杯子摔了。
We get wiser as we get older. 随着年岁的增长,我们也变得聪明些了。
4.用 before 引导:before 表示“在......之前”。
如:Turn off the lights before you go to bed. 睡觉前要关灯。
Before he went to university he was a worker. 上大学之前他是工人。
5.用 after 引导:after 表示“在......之后”。
如:I will tell you after they leave. 他们走我再告诉你。
After you finish the letter show it to me.信写完后给我看看。
6.用 until/ till 引导:until/ till 表示“直到......”
如:He waited until she was about to leave. 他等着一直到她准备离开。
I watched him until he disappeared in the distance. 我瞧着他直到他在远处消失。
**这类句型的主句动词通常只能是延续性动词,不能是终止性动词。但是,在否定句中,主句动词可以是终止性动词,此时构成not...until/till...句式,意为“直到......才......”。
如:She didn’t marry until she was over fifty. 她直到五十多岁才结婚。
We’d better not go until your sister arrives. 我们最好等你姐姐到了再走。
7.用 since 引导:since 表示“自从......以来”。
如:We have known each other since we were children. 我们从小认识。
They’ve moved twice since they got married. 他们结婚后已搬了两次家。
**这类句子的主句通常用现在完成时。但是,当主句表示一段时间时,可用一般现在时代 替现在完成时。如:
如:It’s a long time since we met last. 好久没见面了。
How long is it since you came in London? 你来伦敦有多久了?
二、时间状语从句的时态
(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:
如:Wash your hands thoroughly with hot soapy water before you handle any food.
在拿吃的之前,用热肥皂水把手好好地洗干净。
As soon as the two chicks hatch, they leave the nest burrow. 两只小鸟一出壳就离开了巢穴。
(2)与since从句搭配的主句的时态通常是现在完成时态:
如:Rock and roll has become so commercialized and safe since punk.
摇滚乐自从朋克乐以后就已经过于商业化而缺乏新意了。
The nation's unemployment rate has been climbing steadily since last June.
自去年6月以来,该国的失业率一直在不断上升。
【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,如:
It seems like years since we last met