1、时间状语从句A.when, while, as, whenever;when, while, as 表示主句谓语作和从句的谓语动作同时发生或几乎同时发生。
1.when①When表示点时间时,从句中用短暂性动词;表示段时间时,用持续性动词。
When I got home, my family Were already hav ing dinner.我至U家的时候,全家已在吃晚饭。
(When 表示点时间)When they Were still talking and laughing, the teacher came in. 当他们还在说笑的时候,老师进来了。
(When 表示段时间)He WaVed hello Whe n he SaW her当他看见她的时候,就挥手打了个招呼。
(Whe n 表示点时间)When you think you knoW nothing, you begin to knoW something. 当你认为自己一无所知的时候,就开始知道一些事情了。
(When表示段时间)【注意】当Whe n意思是正当.. 时候(and at that mome nt时,Whe n只能跟在前一分句之后。
He WaS about to go to bed Whe n the doorbel rang他正要上床,忽然门铃响了。
They Were Watching the World Cup When suddenly the lights Went out. 他们正看着世界杯比赛,突然灯灭了。
They had just arrived home Whe n it bega n to rai n 他们刚到家,天就开始下雨了。
②有时When表示虽然,尽管的含义,相当于although或SinCeOHe walks Whe n he might take a taxi.尽管可以打的,但他还是步行。
HoW Can you hope for merCy yourSelf When you ShoW none 既然你不宽恕别人,你自己又怎能希望得至别人的宽恕呢?2.While①while通常表示一段时间,从句中宜用持续性动词作谓语。
Strike while the iron is hot .趁热打铁。
She fell asleep while She WaS reading the n ewspape她在看报的时候睡着了。
②while有时可以作并列连词,表示对比,可译成.... 而.... 。
I am fond of English While he likes math. 我喜欢英语而他却喜欢数学。
We slept while the CaPta in kept WatCh我们睡觉而上尉担任警戒。
③while有时可引导让步状语从句,意思是虽然。
While they love the Children, they are striCt With them. 虽然他们都爱他们的孩子,但却对他们要求严格。
虽然during 与While 意思很相近,但是during 是介词,不能引导从句。
3.as①as表示点时间时,从句中用短暂性动词;表示段时间时,用持续性动词。
as和When两者经常可以通用。
The thief WaS CaUght as Whe n he WaS SteaIi ng in the SuPermarke小偷在超市行窃时被逮住了。
I SaW Jim as Whe n he left the meeti ng rooπ⅛姆离开会议室时候我看到了他。
②as表示一边... 一边.... ,强调从句和主句中两个动作交替进行或同步进行。
They talked as they WaIked 他们边走边聊。
He looked behi nd from time to time as he went.他一边走,一边不时地往后看。
③ as表示随着,此用法不用When或while替代。
AS time goes On ,it's gett ing Warmer and Warmer随着时间的推移,天气变得越来越暖了。
AS SPri ng WarmS the earth, al flowers beg in to bloom随着春回大地,百花开始绽放。
4. When, while, as的用法区别①只有当从句表示的是段时间,即其谓语动词有持续性特征时,这三者可以通用互换。
I got the neWs on the radio When /While /as I Was having breakfast. 我在吃早饭的时候从收音机里获悉这一消息。
②在下列情况下,三者彼此之间不能替换使用:a. as更强调同一时间或紧接的一前一后或伴随着的变化。
We listened to the singer sing as he played the guitar. 我们听着歌星边弹吉它边演唱。
I thought of it just as you ope ned your mouth.你一张嘴我就知道你要说什幺AS he grew older, he became less and less active.着他年龄的增长,他变得越来越不活泼了。
【提示】状语从句可放在主句之前或之后,放在主句之前时一般用逗号与主句分开。
有时可置于主句中间,前后用逗号。
【注意】as引导时间状语从句表示当……的时候”在……期间”时,该从句的谓语通常是那些表示动作意义的动词,而不能是be是、在),have有),like(喜欢),belo ng(属于)等表示状态或静态意义的动词。
【误】I 'm going to the post office.As you—are there, can you get me some stamps? 【正】I 'mgoing to the post office. —While you are there, can you get me some stamps?我打算去邮局。
——当你在邮局的时候,请帮我买几张邮票好吗?正因为as引导时间状语从句表示当……的时候”在……期间”时,从句的谓语不能是表示状态或静态意义的动词,所以当下面第一句变为第二句这样的状语从句时,不能再用as,而应用When:AS a StUde nt he had known great POVerty = When he WaS a StUde nt he had known great poverty.他当学生时,经历过很贫困的生活。
b. when 更强调特定时间,还可表示从句中的动作先于或后于主句的动作,此时不用as 或while。
When I had given Mary the spare ticket, I found my own already gone. 当我把多余的票给了玛丽时,我才发现我自己的票已不知去向。
(从句动作发生在主句之前,注意主从句的时态)When I finally got there, the meeting had been on for ten minutes. 当我最终赶到那里时,会议已开始十分钟了。
(从句动作发生在主句之后,注意时态)c. while 从句只能表示延续的动作或状态或主从句中动作的对比。
She thought I was talking about her daughter, while in fact, I was talking about my daughter.她以为我在谈论她女儿,而事实上,我在谈论我的女儿。
d. 若表示两个短促动作几乎同时发生时,用as场合多于When。
AS he finiShed his speech, the audience burst into applaus他结束讲话时,观众爆发出雷鸣般的掌声。
5.wheneverWhenever是When的强势语,它描述的不是一次性动作,而是经常发生的习惯性动作。
You are always welcome Whe never you come无论你何时来都欢迎。
Whe never We met With difficulties, they Came to help us.每当我们遇上困难的时候,他们就来帮我们。
B.before, after1.beforebefore表示在一段时间之前。
I must finish all the Work before I go home. 回家之前我必须干完所有的活。
YOU must first lear n to walk before you try to run 在想要跑以前,你得先学会走。
He had learned English for three years before he Went to London. 他去伦敦之前已学了三年英语。
She didn ' go out before She finiShed her homework.她把作业做完才出去的。
(=not ................. U ntil ........ )提示:before从句往往带有否定的含义,常译为:还没等到….就….;还没来得及…就... 趁着还没..... 就 ... 。
作此意时,从句中常见情态动词can/ could0He ran off before I could stop him. 我还没来得及阻止他,他就跑掉了。
The man hung UP the phone before I could an SWer 我没坐多久他就回来了。
He almost kno Cked me dow n before he SaW me 他几乎把我撞倒才看至U我。
BefOre I could get in a word, he measured me.我还来得及插话,他就给我量好了尺寸。
I ll Water the flowers before it gets darl我要趁着天还没黑把花浇好水。
Be a pupil before you become a teacher先做学生,后做先生。
【必背】before 常用句型①It will be +时间段+before+ 一般现在时:要等多久才..... .It will be five years before We meet aga in 五年以后我们才能再见。
②It won t be long before一般现在时:等不了多久就会 ....It will not be long before you regret What you have done.不用过多久你就会对你所作所为感到后悔的。