高考英语语法复习状语从句知识讲解在主从复合句中，当一个句子用作状语，起副词作用修饰另一个句子的谓语动词时，这个句子就叫做状语从句。由连词或词组引导。从句位于句首或句中时通常用逗号与主句隔开，位于句尾时可以不用逗号隔开。状语从句共有九类，分别是时间状语从句 ，地点状语从句，原因状语从句 ，条件状语从句 ，让步状语从句，结果状语从句 ，目的状语从句 ，比较状语从句 ，方式状语从句 。 一、时间状语从句1.概念在复合句中，由时间连接词引导的状语从句叫做时间状语从句。2.要点在状语从句中，要注意时态一致。主句是一般将来时，从句要用一般现在时。主句是过去时，从句也要用过去时3.时间状语从句连接词When、 while 、as、before、after、since 、till /until、 by the time 、the first time , each time, every time ,once，whenever，no matter when一就 ： as soon as,immediately, directly, instantly,the moment, the instant, the second , the minute, hardlywhen, scaecelywhen, rarelywhen, no soonerthan.、when, while和asa.when引导的可以是延续性的动词，又可以是瞬间动词。主从句的动作可同时发生，也可之前或之后，When she came in, I stopped eating.她进来时，我停止吃饭。(瞬间动词)When I lived in the countryside, I used to carry some water for him.当我住在农村时，我常常为他担水。（延续性的动词）When I had read the article, he called me.我看完这篇文章之后，她给我打了电话。( 从句动作发生在主句之前)When I got to the cinema, the film had begun.当我到了电影院时，电影已经开演了。从句的动作发生在主句之后注意a.当when和be doing,be about to， be going to do,had just done搭配时，表示“正要做/刚刚做这/那时”。【例】We were about to leave when he came in.我们就要离开，就在那时他进来了。(瞬间动词)b.While引导的从句的谓语动词必须是延续性的，并强调主句和从句的动作同时发生While my wife was reading the newspaper, I was watching TV.(was reading是延续性的动词，was reading和was watching同时发生)While也可以当表示对比（或者相对应）时。【例】I like playing football while you like playing basketball.我喜欢踢足球，而你喜欢打篮球。（对比）c.as引导的动作是延续性也可以是瞬间动词，主句和从句动作同时发生；【例】As we was going out, it began to snow.当我们出门时，开始下雪了。as强调句中两个动作紧接着先后发生，而不强调开始下雪的特定时间,as也可表示“一边一边”，I always sing as I walk.我总是边走边唱。d.这三个连词有时可以互换，有时不可以。It was raining hard when (as) I got there我到那里时，正在下大雨。(动作同时发生，when可换为as, 但不能换为while，因为get是点动词.)He was about to leave, when the telephone rang.他正要离开，忽然电话响了。when不能放在句首。主句动词表达 “正在” “即将”，while, as不能代She thought I was talking about her daughter, while, in fact, I was talking about my daughter.他以为我在谈她女儿，然而，实际上在谈论我女儿。(表转折，对比，when, as都不能代替它)Mother was worried because little Alice was ill, especially as (when/ while) father was away.妈妈担心，因为小爱丽丝病了，特别是他父亲不在家的时候。此时as ,when, while可通用.由before和after引导的时间状语从句。a.before引导的从句不再用否定式的谓语，且当before引导的从句位于主句之后，当主句用将来时，从句总是用现在时；如果before引导的从句谓语用的是过去时，则主句动词多用过去完成时。They had got everything ready before I arrived在我到达之前他们已经把一切都准备好了。The train had left before I arrived at the station在我到达车站之前火车已开走了。b.It is+ time +before才(肯定句中意为才) 【例】It was a long time before I went to sleep again.过了很长时间我才睡着。It was an hour before(until) the police arrived.过了一个小时，警察才来。It will be four days before they come back.他们要过四天才能回来。We had sailed 4 days before we saw the land.The workers worked long hours for two weeks before everything returned to normal工人们长时间地工作了两周后，一切才恢复正常。He was so absorbed in his work that four hours had passed before he knew it他如此专注于工作，不知不觉四个小时就过去了。Time passed quickly and three months went by before he knew it时间飞快地流逝，他没感觉到三个月已过去了。c.It is not +time before（否定句中意为没多久就）It was not long before he learned to tell a story in English.We hadnt run a mile befoe he felt tired.They had not been married four months before they were divorced.d 没来得及，来不及The student rushed out of the classroom before the teacher said a word.Einstein almost knocked me down before he saw me.爱因斯坦几乎把我撞倒才看到我。My father had left for Canada just before the letter arrived.我父亲恰好在信到之前去加拿大了。e.表示“趁着”。We can set off early before it gets hot我们可以趁着天不热早点出发。Youd better write the phrases down before you forget them趁着你还没有忘记，赶紧把这些词组写下来。Please put them away before they are missing趁着他们还没有丢，把它们收好吧。f.表示“宁可。宁愿”，相当于rather than。Id die before I apologized to them我宁死也不向他们道歉。I would be poor before I got money in this way我宁愿穷也不愿用这种方式挣钱。g.after表示主句动作发生在从句动作之后。主句和从句的动作的时间关系正好与before引导的从句相反。【例】After you think it over, please let me know what you decide.你仔细考虑过以后，告诉我你是怎样决定的。After we had finished the work, we went home.完成工作之后，我们回家了。（从句用过去完成时，主句用一般过去时）.由till或until引导的时间状语从句。till和until一般情况下两者可以互换，但是在强调句型中多用until。如果主句中的谓语动词是瞬时动词时，必须用否定形式；I didnt go to bed until（till）my father came back.如果主句中的谓语动词是延续性动词时，用肯定或否定形式都可以，但表达的意思不同。【例】Please wait until I arrived.在我到达之前请等我。I worked until he came back.我工作到他回来为止。I didnt work until he came back.他回来我这才开始工作。Not until the meeting was over did he begin to teach me English.直到散会之后他才开始教我英语。.由since引导的时间状语从句。since引导的从句谓语动词用一般过去时，而主句的谓语动词用现在完成时。在It is 时间since(从以来多长时间了，since +从句或名词，表示一段时间)的句型中，主句多用一般现在时。since引导的从句的谓语动词可以是瞬时动词。I have been in Beijing since you left.自从你离开以来，我一直在北京了。Where have you been since I last saw you?自上次我和你见面以后，你到哪里去了？since引导的从句的谓语动词也可以是延续性的动词，但动词的动作以结束时算起，It is four years since my sister lived in Beijing.我妹妹不在北京住有四年了。It is five months since our boss was in Beijing.我们老板离开北京有五个月了。It is five years since we enjoyed the concert last time.自从上次之后我们已经五年没有欣赏音乐会了。.由by the time引导的时间状语从句。注意时态的变化：在一般情况下，如果从句的谓语动词用一般过去时，主句的谓语动词用过去完成时；如果主句的谓语动词用一般现在时，主句的谓语动