在复合句中充当定语的从句叫定语从句。定语从句的作用相当于形容词，用来修饰主句中的某一名词或代词或整个主句，所以，也称作形容词性从句。被定语从句修饰的词叫先行词，定语从句一般紧跟在它所修饰的先行词之后。在先行词和定语从句之间起连接作用的词叫关系词。关系词有关系代词和关系副词两种。
一、关系代词引导的定语从句
引导定语从句的关系代词主要有who, whom, whose, which, that等。它们分别代替前面的先行词，并在定语从句中作主语、宾语或定语。
A．who
指人，在定语从句中作主语。
What was the name of the man who lent you the money
借钱给你的那人叫什么名字？（定语从句修饰先行词the man）
He who laughs lst laughs best.
谁笑到最后谁笑得最好。（定语从句修饰先行词he）
The chairman of the meeting, who spoke first, sat on my right.
会议主席坐在我右边，他先发言。（定语从句修饰先行词the chairman）
B．whom
指人，在定语从句中做宾语。在口语或非正式文体中，whom可省略或可用who来代替，但在介词后面以及在非限制性定语从句中只能用whom。
There are some people (whomwho)we like and others (whomwho) we dislike.
有些人我们是喜欢的，有些人则是我们讨厌的。（定语从句分别修饰先行词people, others）
The people whomwho I work with are all friendly.
和我一起工作的人都很友好。（定语从句修饰先行词the people）
Mr Carter, whom I spoke to on the phone last night, is very interested in or plan.
昨晚我在电话里和卡特先生交谈过，他对我们的计划很感兴趣。（非限制性定语从句中不能用who代替whom）
Two men, neither of whom I had ever seen before, came into my office.
两个人来到我的办公室，我以前从未见过他们。（在介词后面不用who）
C．whose
通常指人，也可指物，在定语从句中做定语，后面要紧跟被修饰的名词。
There are some people whose faces you can nevr forget.
有些人，他们的脸你永远难以忘怀。（定语从句修饰先行词people）
I saw some trees whose leaves were black because of the polluted air.
我看见一些树的树叶由于空气污染而发黑。（定语从句修饰行词trees）
D．which
1．指物，在定语从句中做主语或宾语。做宾语时常可省略。
English is a language which is easy to learn.
英语是一门容易学的语言。（which在定语从句中作主语，不能省略）
This is a folk song which is now very popular.
这是目前非常流行的一首民谣（which在定语从句中作主语，不能省略）
The river which flows through London is the Thames.
流经伦敦的河叫泰晤士河。（which在定语从句中作主语，不能省略）
The children like cookies (which) my wife makes.
孩子们喜欢我夫人做的饼干。(关系代词which作makes的宾语，可以省略)
2．which引导的非限制性定语从句可以修饰前面的整个主句，相当于and this。
Jim passedhis driving test, which surprised everybody.
吉姆通过了驾驶考试，这使大家都感到惊讶。（定语从句修饰的是整个主句，而不是the driving test）
Sheila couldn't come to the party, which was a pity.
希拉不能来参加聚会，真遗憾。（定语从句修饰的是整个主句，而不是the party）
3．which在非限制性定语从句中有时也可以作定语。
John stayed here for a week, dring which time we visited the West Lake together.
约翰在这里呆了一星期，在此期间我们一起游了西湖。
It might snow this weekend, in which case we won't go to Beijing.
周末可能下雪，在这种情况下，我们就不去北京了。
E．that
指人时，相当于who 或whom；指物时，相当于which。在定语从句中作主语或宾语（做宾语时常可省略）。
He is the man that lives next door.
他就是住在隔壁的那个人。（定语从句修饰先行词the man，作主语）
I don't like stories that have unhappy endings.
我不喜欢结尾悲伤的故事。（定语从句修饰先行词stories，作主语）
The dress (that) Ann boughtdoesn't fit her very well.
安买的衣服不太合身。（定语从句修饰先行词the dress，that作宾语可省略）
Is there anything (that) I can do for you
有我能为你效劳的事吗？（定语从句修饰先行词anything，that作宾语，可省略）
提示：
在口语中，that有时还可以作关系副词，相当于when或介词+which结构。
We left the day (that) he arrived. 他来的那一天，我们就走了。（that替when）
He doesn't see things the way (that) we see them. 他看问题的方法和我们不一样。（that代替in which）
Imagine the speed (that) he drives his car! 很难想象，他开车的速度那么快！（that代替at which）
F．其他关系代词
as 和but也可作关系代词，引导定语从句。
1．as
as可以在限制性定语从句和非限制性定语从句中作主语或宾语。
① 在限制性定语从句中，as可跟在由suc, so, the same修饰的先行词之后。
Such men as heard him were deeply moved.
听过他说话的人，都会深受感动。（as在定语从句中作heard的主语）
I've never heard such stories as he tells.
我从未听过像他讲的这样的故事。（as在定语从句中作tell的宾语）
He lifted so heavy a stone as no one else can lift.
他搬起别人都搬不起的大石头。（as在定语从句中lift的宾语）
比较：
在the same�as结构中，as也可用that代替。但严格地说，the same�as强调相同，the same�that注重同一。
She wore the same dress as her younger sister wore.
她穿着跟她妹妹所穿的一样的衣裙。（as指的是与先行词相似的同类事物）
She wore the same dress that she wore at Mary's wedding.
她穿着她在玛丽婚礼上穿过的同一条连衣裙。（that指的是与先行词同一事物）
② 在非限制性定语从句中，as可代表主句整个句子，引导的定语从句可以放在主句之前或主句之后，一般用逗号与主句分开。
As everyone knows, Taiwan belongs to China.
众所周知，台湾属于中国的领土。
He is from the outh, as we can know from his accent.
他是南方人，这一点我们从他的口音可以知道。
必背：
一些由as引导的定语从句常位于句首，已形成了固定的说法。
as is known to all
这是众所周知的
as has been said before
如前所说
as is often the case
情况常常如此
as may be imagined
这可以想象得出
as has been pointed out
正如已经指出的那样
as often happens
这种情况常常发生
2．but
but作关系词只能引导限制性定语从句，同具有否定意思的主句连用，相当于that�not, who�not或which�not。
There is not a single student in my class but would like to study more.
我班上没有一个学生不愿意多学一点的东西的。（but = who�not ）
There are very few but are against war
很少人不反对战争。（but = who�not）
G．介词+关系代词引导的定语从句
介词+关系代词引导的定语从句是一种非常常见但也比较复杂的定语从句结构。
1. 介词+关系代词中介词的位置
关系代词whom, which在从句中作介词宾语时，可以跟介词一起放在从句与主句之间（that, who不可以），也可以把介词放在从句中有关动词的后面，使关系代词紧跟它所修饰的先行词。
He is a man of rich experience, from whom much canbe learned.
= He is a man of rich experience, whom much can be learned from.
他是个经验丰富的人，从他那儿可以学到很多。
The school in which he once worked is a key school.
=The school (which that) he once worked in is a key school.
他曾经工作过的学校是一所重点学校。
The manager in whosecompany I work pays much attention to improving our working conditions.
=The manager whose company I'm working in pays much attention to improving our working conditions.
我就职的那家公司经理十分注意改善我们的工作条件。
2．介词+关系代词的常见结构
①介词+whichwhom
This is the famous singerabout whom we have often talked.
这就是那位我们经常谈论的著名歌唱家。
Fortunately we had a map, without which we would have got lost.
很幸运，我们带了一张地图，如没有的话，我们就会迷路了。
②名词+of+ whichwhom
Please pass me the book the cover of which is blue. 请把那本蓝封面的书递给我。（也可用whose cover）
③数词+o+ whichwhom
She's got three lucky pens, two of which she never uses.
她有三只幸运笔，其中两只从未用过。
In our school there are about 200 teachers, thirty percent of whom are women. 我校大约有200位教师，其中百分之三十是女教师。
④代词+of+ whichwhom
In the basket I find many apples, some o which have gone bad.
我发现篮子里有好些苹果，有些已经坏了。
There are fifty students in our class, most of whom are from big cities.
我们班有50个学生，其中大多数来自大城市。
Norman won $50,000, half of which he gave to his parents.
诺曼赢得五万美元，他将其中一半给了他父母。
Tom tried on three shirt, none of which he was satisfied with.
汤姆试穿了三件衬衫，都不满意。
⑤最高级+of+ whichwhom
China has thousands of islands, the largest of which is Taiwan. 中国有数千个岛屿，其中最大的是台湾。
⑥介词+which+名词
He usually returns home at ten, at which hour his father locks all the doors ad windows.
他通常十点钟回家，在这时候他爸爸锁好所有的门窗。
His wife got seriously ill, in which case he had to give up the chance of going abroad.
他的妻子病得很重，在这种情况下，他不得不放弃出国的机会。
3．关系代词前介词的选择
在介词+关系代词引导的定语从句中，应注意介词的正确选择。
① 根据后面动词和介词的搭配关系选择。
The two things of which they felt prud were Jim's watch and Della's hair.
他们引以为豪的两样东西是吉姆的手表和德拉的头发。（feel proud of是固定搭配词组）
In the dark street there was not a single person to whom she could turn for help.
在漆黑的街道上没有一个她可以求助的人。（turn to sb. for help是固定搭配词组）
②根据与前面名词的搭配关系选择。
I'll never forget the ay on which I first met him.
我永远忘不了我第一次遇见他的那一天。(the day前面一般用介词on)
Can you imagine a proper situation in which the expression can be used
你能设想一个使用这个词语的场合吗？(a situation前面一般用in)
③有时须同时考虑动词和介词的搭配关系及介词和名词的搭配关系。
Galileo made a telescope through which he could tudy the sky.
伽里略制作了一个望远镜，通过它他得以研究天空。(study the sky through the telescope)
Is that the house in which you once lived
那就是你曾经住过的房子吗？(live in the house)
④根据所要表达的意思来确定。
This is my pair of glasses, without which I cannot see clearly.
这是我的眼镜，离了它我什么也看不清。
注意：
当关系代词在定语从句中作主语时，谓语动词应与先行词的人称和数保持一致。
I, who am your best friend, will do all that I can to help you.
我是你的好朋友，我会尽我一切所能来帮你。
The family, who are fond of music, go to the concert once a month.
这家人很爱音乐，他们每月都去听一次音乐会。
He is one of the boys in ourclass who speak English well.
他是班上英语说得很好的男生之一。（one of +复数名词+关系代词引导的定语从句谓语动词用复数形式）
He is the only one of the boys in our class who speaks English well.
他是班上唯一英语说得很好的男生。（the (only) one the very one the right one of +复数名词+关系代词 引导的定语从句谓语动词用单数形式）
二、关系副引导的定语从句
引导定语从句的关系副词有when, where或 why等。when, where, why分别在定语从句中作状语，在意义上相当于介词+which结构，分别代替表示时间、地点或原因的先行词。
A．when
指时间，在定语从句中作时间状语。
I still remember the day when I first came to this school.
我仍然记得我第一次来到这所学校的那一天。(when= on which)
He came at a time when we needed him most.
他是在我们最需要他的时候来的。(when= at which)
We will never forget the year 1949, when th People's Republic of China was founded.
我们永远忘不了1949年，那是中华人民共和国成立的一年。(when= in which)
B．where
指地点，在定语从句中作地点状语。
I recently went back to the town where I was born.
我最近曾回过一次我出生的城市。(where = in which)
I would like to live in a country where there is plety of sunshine.
我想住在一个阳光充足的国家。(where = in which)
What's the name of the place where you spent your holiday
你度假的那个地方叫什么名字？(where = at which)
C．why
指原因，在限制性定语从句中作原因状语。
Please tell me the reason why you missed the plane.
请告诉我你误机的原因。(why = for which)
Te reason why he was punished is unknown to us.
他受惩罚的原因我们都不知道。
注意:
无论是关系代词，还是关系副词，都在定语从句中取代了先行词，因此，先行词在定语从句中不复出现。
【误】This is the book that I borrowed it yesterday.
【正】This is the book that I borrowed yesterday.
这就是我昨天借的书。（that在定语从句中取代了先行词the book，作borowed的宾语，因此，要去掉it）
【误】The English Corner is the place where people often go there to practise their spoken English.
【正】The English Corner is the place where people often go to practise their spoken English.
英语角是人们经常去练习英语口语的地方。（where在定语从句中取代了先行词the pace，作go的状语，因此，要去掉there）
三、限制性定语从句和非限制性定语从句
根据定语从句在句中所起的作用，可分为限制性定语从句和非限制性定语从句两大类。
A．限制性定语从句
限制性定语从句是先行词在意义上不可缺少的定语，用于修饰和限定先行词。如果去掉，主句的意思就不完整或失去意义。书写时不用逗号与先行词分开。
This is the boy who broke the window.
这就是打破窗子的孩子。（the boy是先行词，who broke the indow是限制性定语从句，明确指出the boy是打破窗子的那个孩子）
I have a book which teaches English grammar.
我有一本讲解英语语法的书。（a book是先行词，which teaches English grammar是限制性定语从句，修饰the book）
The people whom you met in the hall are from Japan.
你在大厅见到的那些人来自日本。（定语从句whom you met in the hall定先行词the people）
B．非限制性定语从句
非限制性定语从句在意义上只是一个附加修饰语，对先行词或主句作些附加的说明。如果去掉，主句的意思仍然清楚。书写时往往用逗号与先行词分开。
I, who am your friend, will share the work with you.
我是你的朋友，将与你分担这项工作。（I是先行词，who am your friend是非限制性定语从句，对先行词I起附加说明的作用）
New Concept English is intended for foreign students, which is known to us all.
新概念英语是专为外国学生编写的，这是我们大家都知道的。（which is known to us all是非限制性定语从句，对主句作进一步的补充说明）
C．在下列情况下，通常使用非限制性定语从句。
1．当先行词表示的是世界上独一无二的人或物时。
The sun, which gives us light and heat, is a fixed star.
太阳是一颗恒星，它给我们光和热。
Last year I visited the People's Great Hall, where many important meetings are held every year.
去年我参观了人民大会堂，每年许多重要会议都要在那里举行。
2．当定语从句修饰整个主句时。
Taiwan belongs to China, as everyone knows.
众所周知，台湾属于中国的领土。
The weather was very terrible, which we hadn't expected.
天气非常糟糕，这点们没有料到。
3．当先行词是专有名词，或先行词本身指示意义十分明确时。
Mr. Joe lives in Beijing now, which is quite a long way from here.
乔先生现在住在北京，那里距离这儿很远。
I congratulate my neighbour, whose son has just won the election.
我祝贺我的邻居，他的儿子刚刚赢得选举。
四、关系代词和关系副词的选用
引导定语从句的关系代词和关系副词的选用，比较复杂除了牵涉到所指的先行词是人还是物，所引导的定语从句是限制性的还是非限制性的，以及关系词在从句中充当什么句子成份外，还要根据习惯用法而定。
A．只用who
在下列情况下，一般不能用that代替who。
1．在非限制定语从句中。
His mother, who loves him very much, is strict with him.
他妈妈十分地爱他，对他要求很严格。
2．先行词是one, anyone, those时。
One who has nothing to fear for himself dares to tell the truth.
一个无所畏惧的人敢说真话。
Anyone who breaks the law shall be published.
任何犯法的人都将受到惩罚。
Those who are against the plan put up your hands please.
凡是反对这项计划的人，请举手。
3．在there here be开头的句子中。
Here is a boy who wants to see you.
有个男孩想见你。
4．先词与定语从句被其他词所分隔时。
Don't tell anyone about the secret who oughtn't to know.
不要把这秘密告诉任何一个不该知道它的人。
I was the only person in my office who was invited.
我是办公室里唯一受到邀请的人。
B． 只用which/whom
在下列情况下，一般不能用that代替which/whom。
1．在非限制性定语从句中。
The weather was very terrible, which we hadn't expected.
天气非常糟糕，这我们没有料到。
2．介词后面。
关系代词紧跟在介词或短语介词后面，只能用which或whom，不能用that。
He climbed up to the top of a large rock, from which he got a good view.
他爬到一块巨大的岩石顶上，从那里他看到很好的景色。（也可用from where）
Sound is a tool, by means of which people communicate with each other.
声音是工具，人们通过这个工具进行交流。
They asked me a lot of questions, most of which I couldn't answer.
他们问了我许多问题，大部分我都不会回答。
C．只用that
在下列情况下，限制性定语从句中一般只用that引导
1．当先行词为everything, anything, nothing, all, none, few, little等词时，或当先行词被every, any, all, some, no, little, few, much等词修饰时。
Everything that they said was true.
他所说的一切都是真的。
He is dead and there's nothing that can be done.
他死了，再也没有什么办法了。
There was little that we could do to help her.
我们没有什么能帮助她的。
These walls are all that remain of the ancient city.
这些墙是这座古城所残存下来的全部。
提示：
something 后面可用which引导定语从句。
There is something(which/that) I'd like to tell you. 有些事我想告诉你。
2．当先行词被序数词或形容词最高级修饰时。
The first place (that) they visited in London was the Big Ben.
在伦敦他们参观的第一个地方是大本钟。
She was probably the hardest working student (that) I have ever taught.
她也许是我教学生中学习最勤奋的。
3．当先行词被the very, the only修饰时。
This is the very grammar book (that) I want to buy.
这正是我要买的语法书。
Beauty is the only thing (that) Emily can be proud of.
美丽是埃米莉唯一能骄傲的东西。
4．当先行词为who或前面有who, which等疑问代词时。
Who that has common sense will believe such nonsense
有常识的人谁会相信这种无聊的事情？
Who is the man that is standing by the gate
站在门口的那个人是谁？
Which is the T-shirt that fits me most
哪件T恤衫最合我的身？
提示：
关系词在定语从句中有三大作用
1. 连接作用——连接先行词和定语从句。
I gave her all the money that I had. 我把我所有的钱都给了她。（that 连接先特词 money和定语从句I had）
2. 替代作用——在定语从句中替代从句所修饰的先行词。
The man who lives nest door is a famous teacher. 住在隔壁的那个人是个名师。（who 替代the man）
3. 成分作用——在定语从句中作主语、宾语、定语或状语。
I like pictures which are painted in the traditional Chinese style. 我喜欢传统的中国画。（which在定语从句中作主语）
5．当先行词为人与事物或动物时。
The driver and his car that fell into the river have not yet been discovered.
掉入河里的司机与车都还没有找到。
The boy and his dog that were believed to be lost in the wood were rescued this morning. 被认为 在森林里迷路的孩子与狗，今天早上已经获救了。
6．先行词在定语从句中做表语时。
She is no longer the sweet girl (that) she used to be.
她再也不是过去那个甜美的女孩了。
He is not the man (that) he seems.
他这人不貌相。
D．关系副词与关系代词的选择
当先行词是表示时间、地点或原因的名词时，定语从句用关系副词还是关系代词来引导，要根据关系词在定语从句中所担当的句子成分来决定。
I will never forget the days when we spent our holidays together.
我永远忘不了我们一起度假的日子。（when作状语）
I will never forget the days which we spent together.
我永远忘不了我们一起度过的日子。（which作we spent宾语）
I know a place where we can have a picnic.
我知道一个我们可以野炊的地方。（where作状语）
I know a place which is famous for its beautiful natural scenery.
我知道一个以自然景色优美而闻名的地方。（which作主语）
E．关系词的省略
在下列情况下，关系代词或关系副词在非正式文体中可以省略。
1．关系代词that, which, who, whom在定语从句中做宾语时，常可省略。
Are these keys (that which) you were looking for
这是你正在寻找的钥匙吗？
The man (who/that) I was sitting net to on the plane talked all the time.
飞机上坐在我旁边的那个人一直在喋喋不休。
2．以the way为先行词的限制性定语从句通常由in which或that引导，而且通常可以省略。
I don't like the way (that in which) she walks.
我不喜欢她走路的样子。
The way (that in which) he answered the questions was surprising.
他回答这些问题的方式令惊奇。
3．在the time when, the place where, the reason why结构中，when, where, why可省略。
I shall never forget the day (when) we first met.
我永远不能忘记我们第一次见面的那一天。
That's the place (where) he stayed when he was in the country.
那就是他在乡下呆过的地方。
F．定语从句与强调句型的区别
1．强调句型中的it是个引导词，本身没有意义。如果去掉it is/was that，句子结构仍然完整，句意也完整。定语从句中的it是指示代词，做主句的主语。如果去掉it is/was that，句子结构不完整，意思也完整。
It is a question that needs careful consideration.
这是一个需要慎重考虑的问题。（定语从句）
It is novels that she enjoys reading.（强调句型）
她喜欢阅读的是小说。（=She enjoys reading novels）
2．在强调句中被强调的部分还可以是副词、介词短语或从句；在定语从句中先行词一般是名词、代词或名词短语。
It was because she was ill that we decided t return. （强调句型）
正是因为她生病了，我们才决定回来。
Was it in this palace that the last emperor died （强调句型）
那位末朝皇帝是在这个宫殿里死的吗？
Was it this palace where the last emperor died （定语从句）
这是那位末朝皇帝死的宫殿吗？
3．有些强调句型中含有一个定语从句，这往往给理解带来一定的难度。解决方法是仔细分析that或who在句中的作用。
It was in the lab that was set up last year that they finished the experiment.
他们是在去年建造的实验室里完成这个实验的。（that was set up last year 是定语从句，that在从句中作主语，并可被which替换）
It was the students who came from our school that won the first prize in the contest.
是来自我们学校的学生获得了竞赛一等奖。（who came from our school 是定语从句，who在从句中作主语）
G．定语从句与同位语从句的区别
1．定语从句是形容词性的，其功能是修饰先行词，起限定作用。而同位语从句等同于它所修饰的名词，是名词性的，其功能是对所修饰的名词作补充说明。
It is a fact (that) you can't deny.
这是一个你不能否认的事实。（定语从句）
It is a fact that she has done her best.
她尽了最大的努力，这是事实。（同位语从句）
2．在定语从句中，that代先行词，在从句中不仅起连接作用，还充当某个句子成分，在作宾语时通常可省略。而在同位语从句中，that只起连接主句和从句的作用，无意义，在从句中不充当句子成分，一般不可省。
The news (that) we heard spread all over the school campus.
我们听到的消息传遍了校园。（定语从句）
The news that Mr. Li will be our new English teacher is true.
李先生将是我们的新英语老师这个消息是真的。（同位从句）
