英语中的各种从句详解

从句

一．名词性从句

在句子中起名词作用的各种从句统称为名词性从句。这类从句在句中可担任主语、表语、宾语和同位语，名词从句可以分为主语从句、表语从句、宾语从句和同位语从句。

1.主语从句

在句子中担当主语的是一个句子，这个从句就叫作主语从句。主语从句可以由下列连词、连接代词和连接副词引导，且不能省略。

连词：that, whether

连接代词：what, whatever, who, whoever 等

连接副词：when, where, how, why

(1)由连词that, whether引导的主语从句

连词that, whether在从句中的作用只是引导主语从句，它在从句中不担任成分，不能省略，且由that, whether引导的主语从句，多用it多形式主语

e.g That the earth is round is true.=It is true that the earth is round.地球是圆的，是一个事实。

Whether he’ll come or not hasn’t been decided.= It hasn’t been decided whether he’ll come or not.

(2)由连接代词或连接副词引导的主语从句

连接代词who, which和连接副词when, where, how, why都可以引导主语从句，它们分别在从句中担任主语、宾语和状语，不能省略，翻译时，不能把它们译为疑问句，由它们引导的主语从句，也可以用形式主语it引导

e.g Who let out the news remained unknown. =It remained unknown who let out the news.谁泄漏了那个消息仍旧无人知道。

When we’ll start is not clear.=It is not clear when we’ll start.我们何时出发还不清楚。

(3)以关系代词what, whatever, whoever, whomever, whichever引导的主语从句不能用形式主语it引导，它们在句子中担任成分，不能省略，语序为陈述语序。

e.g What he said at the meeting is important.他在会上所说的事情是重要的。

Whoever leaves the office should tell me.无论是谁离开办公室都应该告诉我。

(4)用it作形式主语的主语从句结构

a. It is +名词+从句

It is a fact that… 事实是……

It is good news that … ……是好消息

It is a question that … ……是个问题

It is common knowledge that … ……是常识

类似的名词还有：a pity；a wonder；a good thing；no wonder；surprise等。

例如：It is a mystery to me how it all happened.

这一切是怎么发生的是个谜。

It is common knowledge that the whale is not a fish.

鲸鱼不是鱼，这是常识。

It is no surprise that Bob should have won the game.

鲍勃会赢得这场比赛，这不足为奇。

b. It is +形容词+从句

It is necessary that … 有必要……

It is clear that … 很清楚……

It is likely that … 很可能……

It is important that … 重要的是……

类似的形容词还有：strange; natural; obvious; true; good; wonderful; possible; unlikely; quite; unusual; certain; evident; worth-while; surprising; interesting; astonishing, etc.

例如：It is obvious that conductors and insulators are both important in industry.

很明显导体和绝缘体在工业中都很重要。

It is doubtful whether she will be able to come.

她是否能来令人怀疑。

It was really astonishing that he refused to talk to you .

他拒绝和你说话真是令人惊讶。

It is essential that he should be here by the weekend .

周末之前，他应该到这里是必要的。

It seems obvious that we can not go on like this.

很明显我们不能这样下去了。

c. It is +过去分词+从句

It is said that … 据说……

It is reported that … 据报道……

It has been proved that … 已证明……

It must be proved that… 必须指出……

类似的过去分词还有：known; estimated; expected; believed; thought; hoped; noted; discussed; required; decided; suggested; demanded; made clear; found out,etc.

例如：It is thought that he is the best player.

大家都认为他是最好的选手。

It is estimated that the vase is 2000 years old.

据估计这个花瓶有2000年的历史。

It is used to be thought that a new star must be due to a collision between two stars. 过去一直认

为新星是由于两颗星星之间碰撞产生的。

It has not been made clear when the new road is to be opened to traffic.

还没弄清楚这条路将开始通车。

d. It +不及物动词+从句

It seems that … 好像是……

It happened that… 碰巧……

It fo llows that … 由此可见……

It has turned out that … 结果是……

类似的不及物动词还有：seem, appear, occur, follow, happen, turn out, etc. 例如：It turned out that nobody remembered the address.

结果是无人记得那个地址。

It now appears that they are in urgent need of help.

看起来他们急需帮助。

It does not matter if I missed my train, because there is another later.

没有赶上这趟火车没有关系，稍晚还有一趟。

It happened that I saw him yesterday.

碰巧我昨天看见他了。

当“及物动词+ 宾语”较短时，也可用这种结构。

例如：It shocked me that Peter did not tell anybody where he was.

让我吃惊的是彼得没有告诉任何人他在哪里。

It does not interest me whether you go or not.

我对你去不去不感兴趣。

e. It +某些固定结构+ 主语从句。

It doesn’t matter……是无关紧要的……

It makes no difference……毫无区别……

It doesn’t make too much difference that…………关系不大

It doesn’t need to be bothered that……不必担忧……

例如：

It does not make any difference whether it rains or not .

下不下雨没什么分别。

It does not make the least difference to me what you do.

对我来说你做什么都无关紧要。

2. 宾语从句

用作宾语的从句叫宾语从句。

1.引导宾语从句的关联词有三类：

(1) 从属连词that。如：

He told us that he felt ill. 他对我们说他感到不舒服。

I know he has returned. 我知道他已经回来了。

注：that在引导宾语从句时也并不是任何情况下都可以省略。在以下情况下，that不能省略。

1. Everybody could see what happened and that Tom was frightened. 大家都会看出所发生的事情并知道Tom非常害怕。

and连接两个宾语从句，that宾语从句放在and的后面时，that不能省略。

2. I know nothing about him except that he is from the south. 对他我一无所知，只知道他是南方人。

that引导的宾语从句作介词宾语时，that不能省略。

3. That he ever said such a thing I simply don’t believe. 我简直不相信他曾说过这样的话。that从句位于句首时，that不可省略。

4. We decided, in view of his special circumstances, that we would admit him for a probationary period. 鉴于他的特殊情况，我们决定应允他一段试用期。

主句谓语动词与that从句之间有插入语，that不可省略。

(2)从属连词if/whether。如：

I doubt whether he will succeed. 我怀疑他是否会成功。

I don’t know if you can help me. 我不知道你能否帮助我。

(3)连接代词who, whom, whose, what, which, whoever, whatever, whichever

连接副词where, when, how, why。

e.g Who or what he was, Martin never learned. 他是什么人？他是干什么的？马丁根本不知道。

I wonder what he’s writing to me about. 我不知道他要给我写信说什么事。

I’ll tell you why I asked you to come. 我会告诉你我为什么要你来。

2. 介词宾语从句

宾语从句也可用作介词的宾语。如：

He was deeply displeased by what had occurred that day.他对那天发生的事感到很不快。

I walked over to where she sat. 我走向她坐的地方。

有时介词可以省略。如：

I don’t care (for) who marries him. 我不管谁跟他结婚。

Be careful (as to) how you do that. 你要注意做这件事的方式.

注意：连词that引导的名词性从句很少作介词的宾语，只用在except, but, in后。其他一些

介词的宾语从句如果由连词that引导，则需用it先行一步，作形式宾语。

如：He is a good student except that he is careless.他是一个好学生，只是有点粗心。

You may rely on it that I shall help you. 你可以指望我会帮助你的。

3. 动词＋it＋that结构

如果宾语从句后还有宾语补足语，则用it作形式宾语，而将宾语从句后置。如：

We thought it strange that Xiao Wang did not come yesterday.我们认为小王昨天没来是奇怪的。

He has made it clear that he will not give in.他已表明他不会屈服。

4. 某些形容词或过去分词后常接宾语从句，这类形容词或过去分词有sure, glad, certain, pleased, happy, afraid, surprised, satisfied等，连词that可省略。如：

I am not sure what I ought to do.我不能确定我该做什么。

I’m afraid you don’t understand what I said.恐怕你没领会我说的意思。

I’m surprised that I didn’t see all that before.我好奇怪，我以前没看到过。

5. 连词whether (…or not)或if引导的宾语从句

if和whether引导的宾语从句可以互换使用，但whether常和or not连用，if一般不与or not 连用。如：

I wonder whether it is true or not. 我不知它是真是假。

用if引导宾语从句如果会引起歧义，应避免使用if而用whether。试比较：

Please let me know if you want to go.

Please let me know whether you want to go.

(if从句可理解为宾语从句，意为“请告诉我你是否想去”；此句又可理解为条件状语从句意为“如果你想去的话，请告诉我一声”。)

6. 宾语从句的否定转移。在think, believe, suppose, expect等动词后的宾语从句，有时谓语尽管是否定意思，却不用否定形式，而将think等动词变为否定形式。如：

I don’t think you are right. 我认为你错了。

I don’t believe they have finished their work yet. 我相信他们还未完成他们的工作。

3. 表语从句

表语从句放在连系动词之后，充当复合句中的表语, 一般结构是“主语＋连系动词＋表语从句”。可接表语从句的连系动词有be，look，seem，sound，appear等。

如：China is no longer what she used to be.

今日的中国不再是过去的中国了。

The question remains whether they will be able to help us.

问题还是他们能否帮我们。

At that time，it seemed as if I couldn't think of the right word. 当时，我似乎怎么也想不出一个恰当的字眼来。

引导表语从句的关联词的种类：

(1）从属连词that

e.g The trouble is that I have lost his address. 麻烦是我把他的地址丢了。

that是连词,没有词义，在句中不作成分，因此一般不可省略(但在口语中有时that可省略)。

(2) 从属连词whether，as，as if / though引导的表语从句。

如：He looked just as he had looked ten years before.他看起来还与十年前一样。

It sounds as if someone is knocking at the door.听起来好像有人在敲门。

(3) because，why引导的表语从句。

如：That's because he didn't understand me.那是因为他没有理解我（That's because…强调原因）That's why he got angry with me.那正是他对我生气的原因。（That's why…强调结果）

注意：表示结果或名词reason作主语时，后面的表语从句表示原因时要用that引导，不宜用because.

如：The reason why I was sad was that he didn't understand me.我难过的原因是他没有理解我。

(4) 连接代词who，whom，whose，what，which，whoever，whatever，whichever

连接副词where，when，how，why

e.g The problem is who we can get to replace her. 问题是我们能找到谁去替换她呢。

The question is how he did it. 问题是他是如何做此事的。

That was what she did this morning on reaching the attic. 那就是她今晨上了阁楼干的。

(5) 使用虚拟语气的表语从句

在表示建议、劝告、命令含义的名词后的表语从句，谓语动词需用“should+动词原形” 表示，should可省略。常见的词有：advice，suggestion，order，proposal，plan，idea等。

e.g My suggestion is that we （should）start early tomorrow. 我的建议是我们明天一早就出发。

4. 同位语从句

英语中有一些名词如fact, idea, news, word, hope, promise, suggestion, reply, problem, belief, doubt, truth, order, thought等，它们本身有一定的意义，但表达得不够具体。为了使其表达的意义更加具体明确，其后常跟有一个从句，用来补充说明该名词的内容，这个从句就叫做同

位语从句。

(1) 同位语从句的引导词

①表示陈述意义时通常用that。注意that不能省略。

同位语从句说明的名词常见的有：ability, advice, answer, belief, doubt, discovery, fact, fear, hope, idea, information, message, news, order, possibility, problem, proposal, question, story, suggestion, theory, thought, word(消息)等,同位语从句一般都是用来解释说明一些抽象名词，而不可说明的名词是不会接同位语从句的。比如：man, water, sun等具体的人或事物。

e.g There is no doubt that the prices of cars will go down.

The belief that the company will make a great is shared by everyone.

②表示“是否”的意思时只能用whether，不能用if。这一点与主语从句相似。

e.g The question whether he can finish the work within two days remains unknown.

③表示疑问时也可用其他引导词where, when, why, how, who, what来引导。

e.g This student asked a good question why pollution can’t be stopped.

I have no idea where I should go.

I have no idea how I can get to the railway station.

(2) 同位语从句和定语从句的区别

①定语从句相当于一个形容词, 它对先行词起修饰、描述和限制的作用。同位语从句相当于名词，属于名词性从句，它是对前面名词内容的具体表述，它们之间的关系是同位关系。试比较：

The news that you heard is not true. 你听到的那个消息不是真的。（定语从句）

The news that he has died is true. 他已经去世的消息是真的。（同位语从句，说明了news 的具体内容，即he has died）

②同位语从句常跟在news, fact, promise, idea, word, message, hope, truth, answer, proposal, suggestion, order, information 等少数名词之后，而一般名词之后都可跟定语从句。

e.g He didn’t give the answer why he was late. 他没回答他为什么迟到这个问题。（同位语从句）

Then rose a question where we should go. 于是产生了一个问题：我们该到哪里去？（同位语从句）

③that 在定语从句中充当某一成分, 是关系代词; that 在同位语从句中不作任何成分，仅把主句与从句连接在一起，是从属连词。如：

The fact that just now you talked about interests me. 你们刚才谈论的事情使我感兴趣。（定语从句）

The fact that he failed in the exam made his parents very angry. 他考试没及格这个事实使他的父母很生气。（同位语从句）

④when, where, why, how, who, whom, which 如果引导定语从句, 它们分别指前面先行词所

表示的时间、地点、原因、方式、人和物，否则引导的就是同位语从句。试比较：

I still remember the day when he was killed. 我还记得他被害的那一天。(定语从句)

I have no idea when he was killed. 我不知道他什么时候被害的。（同位语从句）

They didn't go to the town where they were born.他们没有去他们出生的小镇。(定语从句) They didn't answer the question where they were born.他们没有回答他们在哪里出生这个问题。（同位语从句）

⑤whether, what 可引导同位语从句，但通常不可引导定语从句。

e.g We have no information whether he is alive. 我们不知道他是否活着。（同位语从句）

Next comes the question what step we should take. 接着的问题是我们下一步该做什么。（同位语从句）

二．定语从句

定语从句（Attributive Clauses）在句中做定语，修饰一个名词或代词，被修饰的名词,词组或代词即先行词。定语从句通常出现在先行词之后，由关系词（关系代词或关系副词）引出。关系代词有：who, whom, whose, that, which等。

关系副词有：when, where, why等。

1. 关系代词引导的定语从句

关系代词所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。关系代词在定语从句中作主语时，从句谓语动词的人称和数要和先行词保持一致。

1）who, whom, that 这些词代替的先行词是人的名词或代词，在从句中所起作用如下：

e.g Is he the man who/that wants to see you?他就是你想见的人吗？（who/that在从句中作主语）He is the man whom/ that I saw yesterday.他就是我昨天见的那个人。（whom/that在从句中作宾语）

2) Whose 用来指人或物，(只用作定语, 若指物，它还可以同of which互换）。

e.g They rushed over to help the man whose car had broken down.那人车坏了，大家都跑过去帮忙。

Please pass me the book whose (of which) cover is green.请递给我那本绿皮的书。

3）which, that 它们所代替的先行词是事物的名词或代词，在从句中可作主语、宾语等，例如：A prosperity which / that had never been seen before appears in the countryside. 农村出现了前所未有的繁荣。（which / that在句中作宾语）

The package (which / that) you are carrying is about to come unwrapped. 你拿的包快散了。(which / that在句中作宾语）

2. 关系副词引导的定语从句

关系副词可代替的先行词是时间、地点或理由的名词，在从句中作状语。

1）when, where, why 关系副词when, where, why的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构交替使用.

e.g There are occasions when (on which) one must yield.任何人都有不得不屈服的时候。

Beijing is the place where (in which) I was born.北京是我的出生地。

Is this the reason why (for which) he refused our offer?这就是他拒绝我们帮助他的理由吗？

2）that代替关系副词

that可以用于表示时间、地点、方式、理由的名词后取代when, where, why和"介词+ which"引导的定语从句，在口语中that常被省略.

e.g His father died the year (that / when / in which) he was born.他父亲在他出生那年逝世了。He is unlikely to find the place (that / where / in which) he lived forty years ago. 他不大可能找到他四十年前居住过的地方。

3. 判断关系代词与关系副词

方法一：用关系代词，还是关系副词完全取决于从句中的谓语动词。及物动词后面无宾语，就必须要求用关系代词；而不及物动词则要求用关系副词。例如：

This is the mountain village where I stayed last year.

I'll never forget the days when I worked together with you.

判断改错（注：先显示题，再显示答案，横线；用不同的颜色表示出。）

（错）This is the mountain village where I visited last year.

（错）I will never forget the days when I spent in the countryside.

（对）This is the mountain village (which) I visited last year.

（对）I'll never forget the days (which) I spent in the countryside.

习惯上总把表地点或时间的名词与关系副词where, when联系在一起。此两题错在关系词的误用上。

方法二：准确判断先行词在定语从句中的成分(主、谓、宾、定、状)，也能正确选择出关系代词/关系副词。

例1. Is this museum ___ you visited a few days ago?

A. where

B. that

C. on which

D. the one

例2. Is this the museum ____ the exhibition was held？

A. where

B. that

C. on which

D. the one

答案：例1 D，例2 A

例1变为肯定句：This museum is ___ you visited a few days ago.

例2变为肯定句：This is the museum ___ the exhibition was held.

在句1中，所缺部分为宾语，而where, that, on which都不能起到宾语的作用，只有the one 既做了主句的表语，又可做从句的宾语，可以省略关系代词，所以应选D。

而句2中, 主、谓、宾俱全，从句部分为句子的状语表地点，既可用副词where，又因in the museum词组，可用介词in + which 引导地点状语。而此题中，介词on 用的不对，所以选A。

关系词的选择依据在从句中所做的成分，先行词在从句中做主、定、宾语时，选择关系代词(who, whom, that, which, whose)；先行词在从句中做状语时，应选择关系副词( where 地点状语，when 时间状语，why 原因状语) 。

4. 限制性和非限制性定语从句

1) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分，去掉它主句意思往往不明确；非限制性定语从句是先行词的附加说明，去掉了也不会影响主句的意思，它与主句之间通常用逗号分开。

e.g This is the house which we bought last month.这是我们上个月买的那幢房子。（限制性）The house, which we bought last month, is very nice.这幢房子很漂亮，是我们上个月买

（非限制性）

2) 非限定性定语从句不能用that引导, 一般用引导词which / as或who（指人），非限定性定语从句既可以修饰主句的部分内容，也可修饰主句的全部内容。as引导的非限定性定语从句既可以放在主句之前，也可以放在主句之后，但which或who引导的非限定性定语从句不能放在主句句首。

e.g As we all know, the moon is a satellite of the earth.

The large area is covered with thick snow, which affects people's life greatly.

His speech, which bored us to death, was over at last.

Her sister, who lived in another city, was coming to visit her.

5. as, which 非限定性定语从句

由as, which 引导的非限定性定语从句，as和which可代整个主句，相当于and this或and that。as一般放在句首，也可以放在句中，which在句中。

e.g As we know, smoking is harmful to one's health.

The sun heats the earth, which is very important to us.

典型例题

1）Alice received an invitation from her boss, ___came as a surprise.

A. it

B. that

C. which

D. he

答案C. 此为非限定性从句，不能用that修饰，而用which.，it 和he 都使后句成为句子，两个独立的句子不能单以逗号连接。况且选he句意不通。

2）The weather turned out to be very good, ___ was more than we could expect.

A. what

B. which

C. that

D. it

答案B。which可代替句子，用于非限定性定语从句，而what不可。That 不能用于非

限定性定语从句，it不为连词，使由逗号连接的两个句子并在一起在英语语法上行不通。

3）It rained hard yesterday, ____ prevented me from going to the park..

A. that

B. which

C. as

D. it

答案B.

as 和which在引导非限制性定语从句时，这两个关系代词都指主句所表达的整个意思，且在定语从句中都可以作主语和宾语。但不同之处主要有两点：

(1)as 引导的定语从句可置于句首，而which不可。

(2)as 代表前面的整个主句并在从句中作主语时，从句中的谓语必须是系动词；若为行为动词，则从句中的关系代词只能用which.。

在本题中，prevent由于是行为动词，所以正确选项应为B。

As 的用法

例1. the same…as；such…as 中的as 是一种固定结构, 和……一样……。

I have got into the same trouble as he (has).

例2. as可引导非限制性从句，常含有'正如'的意思。

As we know, smoking is harmful to one's health.

As is known, smoking is harmful to one's health.

As是关系代词。例1中的as作know的宾语；例2中，它充当从句的主语，谓语动词know 要用被动式。

6. 介词+关系词

1）介词后面的关系词不能省略。

2）that前不能有介词。

3）某些在从句中充当时间，地点或原因状语的"介词+关系词"结构可以同关系副词when 和where 互换。

e.g This is the house in which I lived two years ago.

This is the house where I lived two years ago.

Do you remember the day on which you joined our club?

Do you remember the day when you joined our club?

7. 关系代词that 的用法

1）不用that的情况

a) 在引导非限定性定语从句时。

(错)The tree, that is four hundred years old, is very famous here.

b) 介词后不能用。

We depend on the land from that we get our food.(错)

改为：We depend on the land from which we get our food.

We depend on the land that/which we get our food from.

2) 只能用that，不能用which作为定语从句的关系代词的情况

①当先行词是不定代词时,如:all, little, much, none, one, everyone, something, anything, everything, nothing 等。

e.g That’s all that I could do at that time. 那就是我那是所能为你做的全部。

②当先行词被the only, the very, the same, little, few, no, 等修饰时。

e.g The only thing that I can do is to have a rest.我唯一能做的事情就是休息。

③当先行词被序数词或形容词最高级修饰时。

e.g He was the first person that passed the examination.他是第一个通过这个考试的人。

This is the best way that can solve the problem. 这是解决那个问题的最好办法。

④被修饰词为数词时，只能用that。

e.g Yesterday my mother bought two dogs. Now you can see the two that are playing over there.昨天我妈妈买了两只狗。现在你能看见它们在那边玩。

⑤主句是there be结构，修饰其主语的定语从句that

e.g There is a book on the desk that belongs to Jack.桌上那本书是杰克的。

⑥主句是以which 或who 开头的特殊疑问句时，关系代词只能用that。

e.g Who is the girl that is talking with Mr. Brown？

⑦如果出现两个或两个以上的先行词，并同时兼指人和物时，关系代词用that。

e.g We are talking about the people and countries that we have visited.

⑧如果两个从句，其中一个关系代词已用which, 另一个关系代词应用that，以避免重复。

e.g He built up a factory which produced things that had never been seen before.他办了一家工厂，生产过去从未见到的东西。

三．状语从句

副词性从句（状语从句）

状语从句主要用来修饰主句或主句的谓语。一般可分为十大类，分别表示时间、地点、原因、目的、结果、条件、让步、比较、方式和程度。

1．时间状语从句

(1)常用引导词：when, as, while, as soon as, before, after, since , till,（until ）

特殊引导词：the minute, the moment, the second, every time, the day，the instant, immediately , directly, no sooner …than, hardly …when, scarcely …when

e.g I didn’t realize how special my mother was until I became an adult.

While John was watching TV, his wife was cooking.

The children ran away from the orchard (果园) the moment they saw the guard.

①when, while, as引导时间状语从句时的异同

when引导的时间状语从句中的谓语动词既可以是延续性动词，也可以是短暂性动词；从句的动作可以和主句的动作同时发生，也可以先于主句的动作发生，此时相当于after。当when 从句谓语动词是延续性动词时，可与while互换。

e.g I often missed my home a lot when I was abroad.. ( =while )

When they came home, I was cooking dinner. (不能用while)

When the film ended, people rushed out of the hall. ( =after )

when从句置于主句后面，同时从句中谓语动词又是短暂性动词时，常表示“此时突然……”。

e.g I was walking along the street when I caught sight of a tailor’s shop.

He was enjoying his dinner when a loud noise came on the door.

while引导的动作必须是持续性的，强调主句和从句动作的同时发生，有时侧重主句和从句动作的对比。

He took a bath while I was preparing dinner.

as常可与when, while通用，但它较强调主句和从句动作的同时发生，常译作“边……边”也可用来说明两种正在发展和变化的情况，此时常译作“随着”。

e.g He sang happily as he walked along the path.

The day gets longer and longer as summer comes.

②until, till引导的时间状语从句

主句谓语动词为延续性动词时，主句和从句都用肯定句式，意为“一直到”，表示主句动作一直延续到until/till从句表示的时间才终止；主句谓语动词为短暂性动词时，主句用否定式，从句用肯定式，意思是“一直到才”，表示主句动作到until/till从句表示的时间才开始。

e.g He worked until/till it was dark.

He didn’t work until/till i t was dark.

until和till意义相同，通常可换用，但在强调结构、倒装句或句首，一般用until。

e.g I didn’t know about it until/till he told me.

It was not until he told me that I knew about it.

Not until he told me did I know about it.

③since引导的时间状语从句

since从句中的动词不同，其起算时间也不同。since + 瞬间动词过去时，从该动作发生时起算；since + 延续性动词过去时，从该动作结束时起算。

e.g He has worked very hard since he entered the factory.

(enter为瞬间性动词，该句意为“从他入厂以来，他工作一直非常努力。”)

We haven’t seen each other since I worked in the factory.

(work为延续性动词，该句意为“从我不在工厂以来，我们没见过面。”可说成

We haven’t seen each other since I stopped working in the factory.）

since常用于It’s + some time + since sb. did sth.结构。试比较：

It’s two years since he joined the army. （他参军有两年了。）

It’s two years since he was a soldier. （他退役有两年了）

④before和after引导的时间状语从句

before和after表示的时两个时间活两个事件之间的先后关系。Before引导的从句中的动作通常发生在主句动作之后，如果从句时过去时，主句一般要用过去完成时。After引导的从句中的动作通常发生在主句动作之前，如果主句用过去时，从句一般要用过去完成时。

e.g They had got everything ready before I arrived. 我去之前它们准备好了一切。

After he had worked in the factory for five years, he went abroad. 他在这家工厂工作了5年后出国了。

注意：如果不强调时间的先后，或是因为从句中用的时某个状态动词，before和after句子结构中的谓语动词也可以都用一般过去时。

e.g He arrived after the meeting started. 会开完时他来了。

She did not understand me before I explained it to her. 在我解释给她听之前，她一点都不了解。

⑤as soon as等意为“一……就”的时间状语从句的几种不同表达

as soon as表示“一……就”，在表述已发生的动作时，hardly…when, no sooner…than也可表示同样的意思，但主句谓语动词要用过去完成时，从句用过去时，还可转换成倒装结构。As soon as he saw the policeman, he ran away.

= He had hardly seen the policeman when he ran away.

= Hardly had he seen the policeman when he ran away.

= He had no sooner seen the policeman than he ran away.

= No sooner had he seen the policeman than he ran away.

immediately, directly, instantly, the moment, the minute, the instant,也可引导时间状语从句，相当于as soon as的意思，用法也与as soon as基本相同。上述句子可转换成：

He ran away immediately/directly/instantly he saw the policeman.

He ran away the moment/the minute/the instant he saw the policeman.

2．地点状语从句

常用引导词：where

特殊引导词：wherever, anywhere, everywhere

e.g Generally, air will be heavily polluted where there are factories.

Wherever you go, you should work hard.

注意：where引导的状语从句和where引导的定语从句常可转换，判断它属于哪类从句的关键是看where前面有没有被修饰的、表示地点的先行词。试比较：

Stand where you are! （状语从句）

Stand at the place where you are! （定语从句）

Bamboo grows best where it’s wet and rainy. （状语从句）

Bamboo grows best in plac es where it’s wet and rainy. （定语从句）

3 原因状语从句

常用引导词：because, since, as, since

特殊引导词：seeing that, now that, in that, considering that, given that …

e.g My friends dislike me because I’m handsome and successful.

Now that everybody has come, let’s begin our conference.

①原因状语从句通常由because, since, as引导。because引导的从句可以放在主句前，也可放在主句后面，表示直接的原因或理由，着重点在从句。回答why问句、用于强调结构都用because。

e.g He had to do a part-time job after work because he needed money for his marriage.

It was because he lost it that he found it more valuable than ever.

since和as引导的原因从句更多见于句首，表示明显的、已知的事实，语气比because弱，分别可译作“既然”、“由于”，着重点在主句。

e.g Since you have to stay at home, why don’t you do some shopping on computer?.

As the weather is fine, let’s go fishing.

for也可引导表示原因的句子，但它是个并列连词，通常表示一种推测的原因或附加的说明，语气最弱，一般不放在句首，前面常有逗号分隔。

e.g It must have rained last night, for the ground is wet.

②now that, seeing that, considering that等也可以引导表示原因的从句, 语气相当于since，常译作“既然”，口语中that可省去。

e.g Now (that) my watch has been sold, what’s the use of the watch chain?

Seeing (that) you’re already at the door, I suppose I must invite you inside

4．目的状语从句

常用引导词：so that, in order that

特殊引导词：lest, in case, for fear that，in the hope that, for the purpose that, to the end that

e.g The boss asked the secretary to hurry up with the letters so that he could sign them.

The teacher raised his voice on purpose that the students in the back could hear more clearly.

①目的状语从句通常由(so) that, in order that引导,在口语或非正式文体中，有时也会用that 或so引导。in order that 引导的目的从句可以放在主句后面，也可放在主句前面，而so that 引导的从句通常放在主句后面。目的状语从句中的谓语常含有may(might), can(could), should, will等情态动词。

e.g He always takes a seat in the first row so that/in order that he can hear better.

（也可说成He always takes a seat in the first row so/that he can hear better.但用的较少。）

=In order that he can hear better, he always taked a seat in the first row.

The actress wore ordinary clothes in order that/so that she might not be recognized easily.

=In order that she might not be recognized easily, the actress wore ordinary clothes.

②in case, for fear that, lest 等也可以引导目的状语从句，表示“以防…、以免…” 。

e.g He left early in case he should miss the train.

Take your raincoat in case it rains/should rain.

Mother hid the sweets and chocolates lest/for fear that her son should see them.

5．结果状语从句

常用引导词：so…that, such …that （so + adj./adv. 置于句首，引起倒装）

特殊引导词：such that, to the degree that, to the extent that, to such a degree that

He got up so early that he caught the first bus.

It’s such a good chance that we must not miss it.

To such an degree was he excited that he couldn’t sleep last night.

1）结果状语从句常由so that, so… that, such… that等引导，放在主句之后，so…that与such…that句型在一定条件下可转换。

so+形容词（副词）+that

so+形容词+a(an)+单数名词+that

so+形容词+不可数名词

so+形容词+复数名词

such+a(an)+形容词+单数名词+that

e.g It is such a good story that I’l l never forget it.

It is such a heavy box that nobody can move it away.=It is so heavy a box that nobody can move it.这个箱子太重了没有人能搬的动。

在口语中也可用that引导结果从句。例如：

What have I said that he should be so angry with me?

2）so that引导结果状语从句和目的状语从句的辨别

so that从句之前有逗号的常为结果状语从句，因表示某一行为带来的结果，从句中的时态常为过去式；so that从句中有may(might), can(could), should, will等情态动词的通常是目的状语从句。例如：

I wrote as clearly as possible so that I might get high marks. （目的）

I wrote as clearly as possible, so that I got high marks. （结果）

He went to the lecture early so that he could get a good seat. （目的）

He went to the lecture early, so that he got a good seat. （结果）

3）so, that和so that

这三个连词都可以引导结果状语从句。so that最常用，so和that多用于口语或非正式文体中。so that从句常用逗号同主句隔开。

e.g He made a wrong decision, so that half of his lifetime was wasted. 他做了错误的决定，结果毁掉了半生。

What happened that she looked so worried and disappointed?她看上去如此忧伤、失望，究竟发生了什么事情？

He didn’t abide by the contract, so he was fined. 他没有遵守条约，因此被罚了款。

6．条件状语从句

条件状语从句可分为真实条件句和非真实条件句，非真实条件句在虚拟语气中有详细表述，这里只讨论真实条件句。条件状语从句和时间状语从句一样，表示将来要用一般现在时。常用引导词：if, unless

特殊引导词：as / so long as, only if, providing/provided that, suppose that, in case that, on condition that

We’ll start our project if the president agrees.

You will certainly succeed so long as you keep on trying.

Provided that there is no opposition, we shall hold the meeting here.

注意：

1）有时可以把祈使句作为条件从句，祈使句后面要搭配and，如：

Come tomorrow, and I will tell you. (= If you come tomorrow, …)

Give him an inch and he’ll take a mile. (= If you give him an inch, he’ll …)

2）if only是if的强调式，通常表示说话人的愿望，如：

If only it clears up, we’ll go.

If only somebody had told us, we could have warned you.

If only I hadn’t been late for work. (I wish I hadn’t been late for work.)

3）在真实条件句中，从句动词通常用一般现在时表示将来时间，主句通常带有情态动词，If you move, I’ll shoot you.

If I press this button, what will happen?

If you come, you can see it.

If you finish early, you may go.

注①当从句表示将来已经完成或正在进行的动作时，动词用现在完成时或现在进行时，

I will return the book on Monday if I have read it.

The police won’t take your car away if you are sitting in it.

注②如果从句表示现在的意图、意愿、决心等，则可以用will / shall，如：

If you will read the book, I’ll let you have it.

If you will help me, we can finish by six.

If you will give up smoking / drinking, your health will improve.

4）unless 从句中可用否定词，而if …not 从句中不可再加否定词，因此在unless 引导的否定从句中，不可用if …not 代替unless ，如：

I will go unless no one else does.

I will go if no one else doesn’t. ×

Don’t ask me to explain unless you really don’t understand.

Don’t ask me to explain if you really not don’t understand. ×

7．让步状语从句

常用引导词：though（although）, even if（even though）

特殊引导词：as（用在让步状语从句中必须要倒装；though 可以倒装也可以不倒装），while (一般用在句首, =though)，no matter …, in spite of the fact that, whatever, whoever, wherever, whenever, however, whichever

e.g Much as I respect him, I can’t agree to his proposal.尽管我很尊敬他我却不同意他的建议。The old man always enjoys swimming even though the weather is rough.

No matter how hard he tried, she could not change her mind.

He won’t listen whatever you may say.

让步状语从句的几点说明；

1）though, although不与but连用，但可以和yet, still连用，如：

Though he is over seventy, yet / still / nevertheless he can ride the bike.

2）if 有时也可以用于让步含义，但要注意条件if 与让步if 的区别，试比较：If he is poor, how can he buy the house? (条件)

If he is poor, he is at least honest. (让步) (= even if)

3）even if/though含有退一步想的意思（有时用于虚拟）

e.g I’ll try it, even if/though I may fail. 我会试试，即使我可能失败。

4）as（though）引导让步从句一般不置于句首，而将从句中的表语或谓语动词或状语置于句首，用倒装结构：形容词/副词/动词/分词/名词+though（as, that）+主语+谓语。

①表语的倒装：

Tired as he was, he still went on with his work.

但如果是单数名词或形容词最高级作表语，不再用冠词，如：

Teacher as Michael is, he is not capable of teaching all subjects.

Youngest as he is in our class, he speaks English the best.

②状语的倒装：（这时不可在状语之前加very, much等修饰语）

Much as I admire him as a writer, I do not like him as a man.

Hard as I studied, I could not catch up with them.

③谓语动词的倒装：

Try as he would, he could not remember a word of it. (= No matter how he would try …) Hate him as we may, we must admit his greatness.

5）while (= although),它引导的让步状语从句只能前置，位于句首，如：

While I admit that the problems are difficult, I don’t agree that they cannot be solved.

注意比较下列各句：

While I admit his good points, I can see his shortcomings. (让步状语从句)

While I was reading, the light went out. (时间状语从句)

He is idle, while his brother is diligent. (转折、对比，并列分句)

6）whether…or…引导的让步状语从句为也称为“选择条件-让步状语从句”，可位于主句之前或之后，如：

Whether or not it rains, I’m giving a party tomorrow.

We hold that all countries, (whether they are) big or small, (whether they are) rich or poor, should be equal.

She had to go, whether or not she wanted it.

7）由连接代词whoever, whomever, whatever, whichever, wherever, however引导的让步状语从

句：

“no matter+疑问词”引导让步状语从句相当于“疑问词＋ever”.

no matter who=whoever, no matter what=whatever, no matter which=whichever,

no matter where=wherever, no matter how=however

e.g No matter when/Whenever you call on me, you are welcome.无论你什么时候来都是受欢迎的。

No matter who/Whoever you may be, you have no right to do such a thing. 不管你是谁，你都没有权利做这种事情。

8）注意以上几种结构的省略形式：

e. g However difficult the task (may be), it will be fulfilled on time.

Whatever the difficulties (may be), they must and can be overcome

Though(it was) cold, he still wore a shirt. 天气虽然冷，他仍只穿意见衬衣。

8．比较状语从句

常用引导词：as（同级比较）, than（不同程度的比较）

特殊引导词：the more …the more …, just as …, so…; A is to B what / as X is to Y, no …more than, no …less than, A not so much as B

e.g She is as bad-tempered as her mother.

The house is three times as big as ours.

The more you exercise, the healthier you will be.

Food is to men what oil is to machine. 食物之于人，犹如油之于机器。

9．方式状语从句

1）方式状语从句常由(just) as, as if/though引导，表示动作的方式。

e.g Do exactly as the doctor says.

He walked slowly as if/though he had hurt his leg.

注：在非正式文体中有时会用like代替as引导方式从句。

2）as if/though 引导的状语从句，若描述非事实情况，常用虚拟语气，若描述的是实际情况，用陈述语气。

e.g She treats the orphan as if/though he were her own child.

（他是孤儿，当然就不是她的亲生孩子，故用虚拟语气。）

It looks as if/though it’s going to rain.

（本句用的是陈述语气，说明天真象是要下雨了。）