语法讲座之状语从句
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基本概念
定义：在复合句中由从句表示的状语称作状语从句，它可以用来修饰谓语（包括非谓语动词）、定语或状语，或是整个句子。状语从句通常由一个连词引起，也可以由一个起连词作用的词组引起，有时甚至不需要连词直接和主句连接起来。状语从句一般分为九大类（见下表）：
状
语
从
句
类别
时间状语从句
地点状语从句 原因状语从句 目的状语从句 结果状语从句 条件状语从句 方式状语从句 比较状语从句 让步状语从句
1．时间状语从句： 在时间状语从句中，要注意时态一致，一般情况下主句是将来时的时候，从句要用一般现在时。可以引导时间状语从句的连词很多，根据意义和主从句之间的时间关系，又可分类如下：
(1) 表示同时性，即主从句的谓语动作同时发生或几乎同时发生。其连词有：when （当……的时候）, while（当……的时候）, as（当……的时候）, as soon as（一……就……）, once（一旦……）等。如：
Strike while the iron is hot.趁热打铁。
While I am washing the floor, you can be cleaning the windows.（while含有对比的意思）
我洗地板的时候，你可以擦窗户。
As / When I came home, I met an old schoolmate of mine.我回家的时候遇到了我的一位老同学。
I´ll ring you up as soon as I get an answer from him.我一有他的答复就给你打电话。
Once you see him, you will never forget him. 你一旦见过他，就不会忘了他的。
　
(2) 表示先时或后时，即主句的谓语动作发生在从句之前或之后，主要连词有：after（在……之后）, before（在……之前）, when(=after)等。如：
After / When the children had gone to bed, she began to prepare her lessons.（从句的动作发生在主句的动作之前，所以从句用了过去完成时） 孩子睡觉了以后她开始备课。
He had learned English for three years before he went to London.（主句的动作发生在从句的动作之前，所以主句用了过去完成时） 他去伦敦之前已学了三年英语。
It was not long before I forgot it all.(It is / was / will be …before…是常用句型)
He ran off before I could stop him.（主句和从句的动作几乎同时发生，时态一致）
我还没来得及阻止他他就跑掉了。(注意before在汉语中的译义)
(3) 表示习惯性、经常性，即从句描述的不是一次性动作，而是经常发生的习惯性动作。主要连词有every time（每次）, each time（每次）, whenever（每当）等。例如：
Whenever 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。
Each time he came to town he would visit our school.他每次进城，总要来看看我们的学校。
Every time I went to his house, he was out.我每次去他家，他都出去了。
（4）表示持续性或瞬间性，主要连词有：since（自从）, ever since（自从）, until（直到……才/为止）, till（直到……才/为止）等。如：
It is just a week since we arrived here.（It is /was… since…是常用句型）
我们到这儿刚刚一星期。(主句的动作或状态持续时间较短，不能用ever since)
You have been reading to me ever since James went out.（ever 放在since之前是用来表示说话者强调主句动作或状态持续时间长） 自从James走后你一直在给我朗读。
The big clock which used to strike the hours day and night was damaged during the war and has been silent ever since.( ever since可以放在句末， since则不能)
这只一向日夜不停打点报时的大钟在战争中损坏了，从此就一直不响了。
My uncle went to Tibet in 1951. He has been living there ever since.我叔叔于1951年去了西藏，从那以后他一直生活在那里。
Things went well until / till one night an accident happened.事情一切正常，直到有一天晚上发生了意外。
I knew nothing about it until / till he told me.(但Until he told me, I knew nothing about it. “till”不位于句首。)他告诉我了我才知道。
2． 地点状语从句 地点状语从句是由where（在……的地方）, wherever（无论哪里）引导的：
Wuhan lies where the Yangtze and the Han River meet.武汉位于长江和汉水汇合处。
Where there is a will, there is a way.有志者，事竟成。
You´d better make a mark where you have any questions.(这里where引导的从句不是定语从句)
哪儿有问题，你最好在哪儿做个记号。
He would keep in touch with us wherever he was .他无论在什么地方，总是与我们保持联系。
3． 原因状语从句
表示原因的状语从句可以由as（由于）, because(因为), since（既然）, now (that) （既然）, considering that（顾及到）, seeing that（由于）等连词引导：
I do it because I like it.因为我喜欢我才干。(because不能与 so连用)
He couldn´t have seen me, because I was not there.他不可能见过我，因为当时我不在那儿。
Seeing (that) quite a few people were absent, we decided to put the meeting off.由于好些人都没到会，我们决定延期开会。
Now that/Since you are all here, let´s try and reach a decision.既然大家都来了，咱们就设法做出一个决定吧。
As she was ill, she didn´t come to the party.由于病了，她没来参加晚会。
Considering that they are just beginners, they are doing quite a good job.考虑到他们才刚刚学做，他们干得算很不错的了。
4． 目的状语从句 引导目的状语从句的主要连词有:that, so that（以便）, in order that（为了）, for fear that（以便）, in case（万一）等，从句中常常使用一些情态动词，如：can, could, may, might, should等。如：
Let´s take the front seats (so) that we may see more clearly. 我们坐前排吧，这样我们看得更清楚些。
School was closed early in order that the children might go home ahead of the storm.早点儿放学是为了让孩子们在暴风雨到来之前回家。
He took the name down for fear that he should forget it.他把名字写下省得忘了。（该从句中一般用情态动词should+动词原形，或省略should）
Better take more clothes in case the weather is cold.最好多带些衣服以防天气会冷。
5． 结果状语从句
引导结果状语从句的连词有：that, so that（从句中不带情态动词）, so…that(如此……以致……), such…that(如此……以致……)等。
What has happened that you all look so excited? 发生了什么事，使你们都显得如此兴奋？
He didn´t plan his time well, so that/so he didn´t finish the work in time.他没把时间计划好，结果没按时完成这项工作。
We left in such a hurry that we forgot to lock the door. 我们走得匆忙，把门都忘了锁了。（such是形容词，后接名词）
The village is so small that it cannot be shown in the map.这村子太小，所以这地图上没有。（so是副词，后接形容词或副词）
Jenny is such a clever girl that all the teachers like her very much = Jenny is so clever a girl that….Jenny是如此聪明的女孩，以至老师们都非常喜欢她。
但是，当名词前有many, much, few, little(少)修饰时，要用so,不能用such。例如：
I have had so many falls that I am black and blue all over.我摔了许多跤，以至于浑身青一块，紫一块。
He has so few friends that he often feels lonely.他朋友很少，所以经常感到孤独。
I had so little money then that I couldn´t afford a little present.我当时囊肿羞涩，连一份小小礼物都买不起。
6． 条件状语从句 表示条件的状语从句可以由if（如果）, unless（除非）, in case（万一）, so /as long as（只要）, as/ so far as（就……而言）, on condition that（条件是……）, suppose（假设）, supposing（假设）（仅用在问句中）等词或词组引导。一般情况下当主句是将来时的时候，从句要用一般现在时。
As/So long as we don´t lose heart, we´ll find a way to overcome the difficulty.只要我们不灰心，我们就能找到克服困难的方法。
Send us a message in case you have any difficulty.万一你有什么困难，请给我们一个信儿。
If you leave at 6 o´clock tomorrow morning, you´d better get to bed now.如果你明早6点钟走，你最好现在就上床。
We´ll let you use the room on condition that you keep it clean and tidy.只要你能保持整洁，我们可以让你使用这个房间。
As/So far as I know, he is an expert on DNA.据我所知，他是一个DNA专家。
He´ll accept the job unless the salary is too low/ if the salary is not too low.他会接受这项工作的，除非薪水太少/如果薪水不太少的话。
Suppose/Supposing we can´t get enough food, what shall we do?假设我们弄不到足够的食物，那我们怎么办？
7． 方式状语从句 方式状语从句常由as（与……一样）, as if（仿佛）, as though（仿佛）等词引导：
Do in Rome as the Romans do.入乡随俗。
Leave things as they are.让一切顺其自然。
She stood at the door as if (=as though) she were waiting for someone.她站在门口，仿佛在等人似的。（由as if或 as though引导的从句中可用虚拟语气）
8． 比较状语从句 比较状语从句常由than（比）, as（与……一样）等词引导：
It rains more often in Shanghai than in Beijing.上海下的雨比北京的多。
Our country is as big as the whole of Europe.我们的国家同整个欧洲一样大。
The result was not as/so good as I had expected.结果不如我预料的那么好。
The busier he is, the happier he feels.（常见句型）他越忙越开心。
9． 让步状语从句 让步状语从句由although（尽管）, though（尽管）, however（无论怎样）, whatever（无论什么）, whoever（无论谁）, whomever（无论谁）, whichever（无论哪个）, whenever（无论何时）, wherever（无论哪里）, whether（是否）, no matter (who, what, where, when, etc) （无论……）, even if（即使）, even though（即使）等词引导。如：
We won´t be discouraged even if(=even though) we fail ten times.我们就是失败十次也不泄气。
It was an exciting game, though / although no goals were scored.那是一场精彩的球赛，尽管一个球都没进。(though, although不能与 but连用)
Whether you believe it or not, it´s true.不管你信不信，这是真的。
However (=No matter how) expensive it may be, I´ll take it.无论它有多贵，我也要买下它。
Don´t let them in, whoever(=no matter who) they are.不管他们是谁，别让他们进来。
No matter what I say or how I say it, he always thinks I´m wrong.无论我说什么或怎么说，他总认为是我错。
连词as也可以引导让步状语从句，但从句中要用特殊语序。如：
Young as he is, he knows a lot=Though he is young 或Young though he is, he….
他虽然年轻，但懂得很多。(though 也有这种用法，可以替换as,但although没有这种用法)
though还可以用作副词，放在句末。如：
It was hard work;; I enjoyed it, though=It was hard work, but I enjoyed it.那工作很苦，但是我喜欢干。
　

重点疑难
1． as, when, while的区别
as, when, while都表示主、从句的动作或状态同时发生，但三者意义不尽相同。as和when引导的从句既可表示一点时间，也可表示一段时间，从句中的谓语动词既可以是持续性动词，也可以为短暂性动词，经常可以互换使用；while引导的从句通常表示一段时间，从句中宜用持续性动词作谓语。当从句中的谓语动词为持续性动词时，这三者可以通用（前面例句中已有体现），再如：
Mother was worried because little Alice was ill, especially as / when / while father was away in France.妈妈担心，因为小艾丽思病了，特别是当父亲远在法国的时候。
如果从句和主句要表示一个人的两个动作交替进行或同时完成时，则多用as，可译为“一边......，一边......”。例如：
He looked behind from to time as he went.他一边走，一边不时地往后看。
As time goes on, it´s getting warmer and warmer..随着时间的推移，天气变得越来越暖了。
I thought of it just as you opened your mouth.你一张嘴我就知道你要说什么。（若表示两个短促动作几乎同时发生时，用as的场合多于when.）
当主从句之间表示转折或对比关系时，多用while, 不用as或when。如：
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。
如果表示从句的动作在主句的动作“之前”或“之后”发生时，多用when（=after）, 不用as或 while。此外，when还含有“at that moment”的意思（= and then），引起的句子不能放在句首，也不能用as, while来替换。例如：
He was about to leave when the telephone rang.他正要离开，忽然电话铃响了。
We were watching TV when suddenly the lights went out.我们正在看电视，突然灯灭了。
They had just arrived home when it began to rain.他们刚到家，天就开始下雨了。
2． until与till及 not…until / till的用法
（1）until和till都可表示“直到．．．．．．为止”，与持续性动词的肯定式连用。如：
He waited until / till we finished our meal.他一直等到我们吃完饭。
（2）当until和till表示“直到．．．．．．才．．．．．．”时，通常与短暂动词的否定式连用，这时，until和till也可用before代替。如：
I didn´t leave until / till / before she came back.直到她回来，我才离开的。
(3) be动词的肯定式和否定式都可以和until或till连用。
(4) until引导的从句可以放在主句之前或主句之后，但till从句一般不放在句首。如：
Until he told me, I knew nothing about it.他告诉我了我才知道。
当not until位于句首时，主句中的主语、谓语要使用倒装语序：
Not until she came back did I leave.
在强调句型中一般用until，不用till。如：
It was not until she took off her dark glasses that I realized she was a famous film star.
( It is /was … that…是常见的强调句型结构 )直到这位大明星摘下墨镜，我才认出她。
4． 有时，the time（当……的时刻）, the moment（当……的时刻）, by the time（到……时候为止）, next time(下次), the first time(第一次……的时候), the last time(上次……的时候)，immediately（一……就……）, instantly（一……就……）, directly（一……就……）等词或词组以及hardly /scarcely…when…（刚……就……）, no sooner…than…（刚……就……）等关联词也可引导表示时间的状语从句，例如：
Be sure to call on us next time you come to town.下次你进城一定来看我们。
By the time he was fourteen, Einstein had learned advanced mathematics all by himself. (by意为“到．．．．．．为止”，引起的从句中为一般过去时，主句中用过去完成时)
爱因斯坦到十四岁时就自学完了高等数学。
She rushed into the room immediately / the moment she heard the noise.她一听到这声音，就冲进房间。
He left me a good impression the first time I met him.我第一次见他时，他给我留下了好印象。
He had no sooner arrived there than he fell ill.他刚到达那里就生起病来。
He had hardly finished when someone rose to refute his points.他还没全说完，就有人起来反驳他的论点。
She had scarcely fallen asleep when a knock at the door awakened her.她刚要睡着，忽然敲门的声音把她惊醒。
当hardly, scarcely, no sooner位于引起的句子的开头时，常用倒装语序。上面的例句可以依次改写成：
No sooner had he arrived there than he fell ill.
Hardly had he finished when someone rose to refute his points.
Scarcely had she fallen asleep when a knock at the door awakened her.
值得一提的是，这三组关联词引起的句子中，前面常用过去完成时，后面用一般过去时。
5.if和unless的用法
一般情况下，unless相当于if…not，可以互换。如：
I won´t let you in unless you show me your pass = I won´t let you in if you don´t show me your pass.如果你不出示通行证，我就不让你进来。
但是，在下列情况下，两者是有区别的。（1）unless引导真实条件句，if…not可以引导真实条件句或非真实条件句。（2）unless从句中有否定词时，不能换成if…not结构。（3）如果主句描述的是情感或情绪活动方面的内容，if…not结构不能换成unless。如：I´ll be quite glad if she doesn´t come this evening.(她今晚如果不来我很高兴。)（4）unless表示唯一条件，不能用and连接重复使用，if…not则可以。
6.because, since, as, for的区别
（1）在这四个连词中，because语气最强，它引导的从句表达的是未知的新信息，也是该主从复合句中的焦点，一般都置于主句之后（也可以放在主句之前，用逗号隔开）。在回答”why”引导的特殊疑问句时，一般只能用because；在强调结构”It is/was …that …”中，也只能用because。此外，在关联词“not …but …”结构中，也用because引导的原因状语从句。例如：
It´s because he helped you that I´m prepared to help him.正是因为他帮助过你，所以我乐意去帮助他。
----Why didn´t you phone me last night?你昨天夜里为什么没给我打电话？
----Because I didn´t want to disturb you.因为我不想在夜里打扰你。
He decided to give up the chance of going aboard, not because he did not want to but because his wife was ill.他决定放弃出国的机会，不是因为他不想去，而是因为他妻子病了。
（2）since和as语气不如because强，as的语气最弱。他们引导的从句大多置于句首，有时放在主句之后（as从句在复合句中的位置更为灵活），表达的往往是已知信息，即所指的原因是人们已知的客观事实，所以，复合句的重心在主句，不在从句。例如：
Since you have no license, you are not allowed to drive.因为你没有驾驶执照，所以不允许你开车。
As he was not well enough, I had to go without him.由于他身体欠佳，我只好不带他去了。
（3）for的语气不及because, since, as强，为并列连词，引导的分句常放在主句之后，从句前通常用逗号，表示说话者为所做的推断和预测提供理由，或对前一分句进行补充和解释。如：
It must have rained last night, for the ground is wet.(for分句表示说话者推断“昨晚天下雨”的理由。此时，because不能替代for，因为地湿不是造成下雨的直接原因。原句可改为：The ground is wet, for / because it rained last night.)
7．有些表示时间、地点、条件、方式或让步等的状语从句中，如果谓语含有动词be，主语又和主句中的主语一致，或者主语是it，常把从句中的主语和谓语的一部分（特别是动词be）省略掉。例如：
Look out for cars when crossing the street(= when you are crossing …).过街时当心车辆。
She hurriedly left the room as though /if angry (= as though/if she was /were angry…).
她急匆匆地走出屋去，好象很生气的样子。
If possible, I´d like to have two copies if it (= if it is possible,…). 可能的话，我想要两本。
She advised me not to say anything unless asked (= unless I was asked ).
她劝我别说什么，除非有人要我说。
As a young man, he studied law and became a lawyer(= As/ When he was a young man,…).他年轻时就学了法律，并当了律师。
　

专项练习
1. you decide to take up, you should try to make it a success.
A. If B. Whenever C. Unless D. Whatever
2.It is foolish to take a taxi you can easily walk to the station.
A. before B. that C. unless D. when
3.I´ll accept any job, I don´t have to get up early.
A. even though B. though C. in case D. as long as
4. ­­­___________ problems you have, you can always come to me for help.
A. What B. Whatever C. Whichever D. Which
5. much advice I gave him, he did exactly what he wanted to do.
A. How B. Whatever C. However D. No matter
6. ----Did you remember to give Mary the money you owed her?
---- Yes. I gave it to her I saw her.
A. while B. the moment C. suddenly D. once
7. If we work with a strong will, we can overcome any difficulty, great it is.
A. what B. how C. however D. whatever
8.I hurried I wouldn´t be late for class.
A. since B. so that C. as if D. unless
9.John plays football , if not better than, David.
A. as well B. as well as C. so well D. so well as
10. ----What was the party like?
----Wonderful. It´s years I enjoyed myself so much.
A. after B. when C. before D. since
11．Don´t change your mind, happens to you.
A. which B. what C. whichever D. whatever
12.___________ he comes, we won´t be able to go.
A. Without B. Unless C. Except D. Even
13.Nobody believed him ____________ what he said.
A. even though B. even if C. no matter D. because
14.I was watching TV ____________ suddenly the lights went out.
A. when B. while C. as D. for
15.Take your umbrella with you ____________ it rains.
A. if B. as if C. in case D. as long as
16.No sooner ____________ entered the office ___________ I heard the telephone ringing.
A. had I, when B. I had, than C. had I, than D. I had, when
17.I had hardly arrived ___________ he started crying to go home.
A. as B. for C. when D. until
18.It won´t be long ___________ you regret what you said.
A. since B. when C. before D. till
19.The new secretary is supposed to report to the manager as soon as she__________.
A. will arrive B. arrives C. is going to arrive D. is arriving
20._____________ the day went on, the weather got worse.
A. With B. Since C. While D. as
Keys: 1—5 DDDBC 6—10 BCBBD 11—15 DBCAC 16—20 ACCBD


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