定语从句
所谓从句，就是一个主谓结构相当于整个句子(这样的句子叫复合句)的一个成分，因此从句不能单独使用。在复合句中修饰名词或代词、作定语的句子叫定语从句。定语从句是中国人学英语最重要的难点之一。
其实定语从句很有规律，总结如下:在关系代词中that既可指人又可指物、既可作主语又可作宾语，因此，除了在非限定性定语从句中，用that一般不会出问题。
关系副词的用法比较单一，它们从句中只起状语的作用，表示时间的就用who门，表示地点的就用where，而why只修饰一个词，即reason。
定语从句所修饰的词叫“先行词”，因为它总是处在定语从句的前头，比定语从句先行一步。
引导定语从句的词叫关系词，包括关系代词和关系副词。
关系代词：
who，which，that作从句的主语
whom，which，that作从句的宾语(可省略)
whose从句中作定语
以下情况只能用that，不能用which:
i. 先行词为不定代词all, little, none，any，every，no，much, anything, nothing
ii. 先行词有最高级和序数词修饰时(包括: the only, the very, the same, the last, the next等)
iii. 先行词既有人又有物的时候
以下情况只能用which，不能用that;
① 引导非限制性定语从句(包括代表整个主句的意思时)
② 介词 关系代词的结构中
关系副词：
when指时间，在定语从句中作时间状语
where指地点，在定语从句中作地点状语
why指原因，在定语从句中作原因状语，只修饰reason。
如果用定语从句把两个句子合二为一：首先找出两个句子当中相同的部分，定语从句修饰的就是这一部分。要把其中一个句子变成定语从句，就要把这句中相同的那个部分用一个关系词来代替;代替时，先看被代替的部分是指人还是指物、再看它作什么句成分。指人并作主语的，就用who。或that;指人并作宾语的，就用whom或that;指人并作定语的，就用whose。指物并作主语的，就用which或that认指物并作宾语的，还是用which或that认是物并作定语的，就用whose或of which。这样找好并替换以后，再把这个关系代词放到要变成定语从句的那个句子的最前面(被代替的部分不能再保留，其它的词语一律不变)，这个句子就变成了定语从句。然后，再把这个定语从句整个放在被修饰的词后面，最后，如果还有其它句子成分，就把它们放到定语从句的后面，就行了。例如：
Have you found the book? You were looking for the book yesterday.
在这两个句子中，the book是相同的，定语从句修饰的就是the book。把后面这一句变成定语从句，找个关系词来代替the book;在将要被变成定语从句的名子中，the book是物并作宾语，所以用which或that代替它。
然后把which或that放到本句的最前面，其它的词和语序一律不变。这时，就成了"that/which you were looking for yesterday?”，再把这个定语从句整个放在被修饰的词后面，就成了“have you found the book that/which you were looking for yesterday?”定语从句就完成了，主句是问句，所以句末用问号。that/which代替的是原句中的宾语，原句变成了从句，它们仍然作从句的宾语。关系代词在从句中作宾语时可以省略，因此上句又可变成“have you found the book you were looking for yesterday?”.
关系副词与此同理。只是关系副词代替的是原句中的状语。在被代替之前，这个状语中一定要含有一个与另一句相同的成分。
例如：This is the house where I was barn and brought up in the house.在这两个句子中，in the house是句子里的地点状语，定语从句修饰的就是the house。把后面这一句变成定语从句。在将要被变成定语从句的句子中，in the house是地点状语，所以用where来代替它。然后再把where放到本句的最前面，其它的词和语序来代替它。然后再把where放到本句的最前面，其它的词和语序一律不变。这时，就成了"where}was barn and brought up"。再把这个定语从句整个放在被修饰的词后面，就成了"This is the house where I was barn and brought up.”，定语从句就完成了，主句是陈述句，所以句末用句号。Where代替的是原句中的状语，原句变成了从句，它就作从句的状语。
那么，“介词 关系代词”是怎么回事呢?原来上面这个例句，还有一种做法：This is the house. I was born and brought up in the house.在这两个句子中，the house是相同的，定语从句修饰的就是the house 。把后面这一句变成定语从句。在将要被变成定语从句的句子中，the house表示物而且是介词in的宾语，所以用关系代词which或that来代替。然后把which或that放到本句的最前面，其它的词和语序一律不变。这时，后面这一句就成了 “which/that I was born and brought up in”。再把这个定语从句整个放在被修饰的词后面，就成了“This is the house which/that I was born and brought up in”。定语从句就完成了，主句是陈述句，所以句末用句号。
which/that代替的是原句中的宾语，原句变成了从句，它们就作从句的宾语。关系代词在从句中作宾语时可以省略，因此上句又可变成“This is the house I was born and brought up in.”
但是，in可以提到关系代词的前面，不过这时不能用that，而且不能省略。所以上句又可变为“This is the house in which I was born and brought up.”这就是“介词 关系代词”的来历。
定语从句又分为限定性定语从句和非限定性定语从句。限定性定语从句把它的先行词限定在特定的意义之内，对先行词起限定的作用、是先行词必不可少的修饰语，没有它，整个句子的意思就会受到影响、就不完整。非限定性定语从句不对先行词起限定的作用，不是先行词必不可少的修饰语，只对先行词起补充说明的作用，没有它，整个句子的意思不会受到影响、仍然完整。非限定性定语从句相当于一个分句，翻译时也是把它当作分句处理的。非限定性定语从句和它的先行词之间要用逗号隔开;而限定性定语从句和它的先行词之间不能用逗号隔开。非限定性定语从句中除了不用that以外，其它关系词都可使用，使用方法与限定性定语从句一样。
例如：The supermarket which was opened two months ago is now closed down. 两个月前开的那家超市现在已经*了。(限定)
The supermarket, which was opened two months ago, is now closed down. 那家超市现在已经*了，那家超市两个月前开的。(非限定)
The book(which) you’re reading is mine . 你正在读的那本书是我的。(限定)
The book, which you’re reading, is mine. 那本书是我的，你正在读那本书。(非限定)
如果以上例子的差别不十分明显，再看下面的例句：
I’ve been to London , which is a beautiful city. 我去过伦敦，那是个美丽的城市。
Your father, whom I respect very much, is a kind old man. 你父亲是个很和善的老头，我很尊重他。
Nanjing, where I lived for five years, is very hot in summer. 南京夏天非常热，我在那里生活过五年。
在以上三例当中，定语从句不就能是限定性的。若变成限定性定语从句，其意就成了“我去过那个是座美丽的城市的伦敦。你那个我很尊重的父亲是个很和善的老头。我在那里生活过五年的南京夏天非常热。”言外之意是还有别的伦敦、父亲和南京。
通过这几个例子我们可以看出，专用名词以及世界上独一无二的东西都不能有限定性定语从句。因为它们的意义本身已经非常清楚，不需要对其进行限定。另外，非限定性定语从句的先行词还可以是整个主句所表达的意义。
如：He did well in the physics exam, which surprised me.他物理考得很好，这使我很吃惊。
(学地道的英语有两个重要的练习方法：parallel writing, and reverse translation，即平行写作和逆翻译。所谓平行写作，就是模仿英语的句子写类似的句子。而逆翻译就是先把英语译成汉语，或根据汉语的译文，再把汉语翻译成英语，再把英语译文同原文比较，分析差异。这两种方法能避免汉语式英语。)
He did well in the physics exam, which surprised me. 他物理考得很好，这使我很吃惊。
请把这句话逆翻译。有的同学会翻译为：He did well in the physics exam, this surprised me. 这句话错在什么地方呢?错在句法。这句话有两个主谓结构，是两个并列的分句，但没有连词(this 是代词)，这就成了串句。
再如：He’s very particular about wording, which I am not. 他很咬文嚼字，而我不。
I said nothing, which made her angry. 我什么也没说，这使她很生气。
Tom didn’t go to the show, which was a pity. 没去看演出，这很遗憾。
注意各个关系词的用法：
1.指人的关系代词：who, whom, whose, that 的用法：
(1)作主语(who, that )
Those who are going to play in the match are to meet at the gate at 1:30 after lunch. 那些参加比赛的人午饭后1：30在大门口集合。
在本句中，先行词是those;关系代词who引导定语从句，同时代替先行词在从句中担任动词are going to play 的主语。
The man who/that is talking with Mr. Wang is a famous doctor. 正在和王先生说话的那个人是一个有名的医生。
在本句中，先行词是the man;关系代词who/that引导定语从句，同时代替先行词在从句中担任动词is talking的主语。
这个复合句可以还原成两个句子：The man is a famous doctor. He is talking with Mr. Wang.
(2)作宾语包括作介词宾语(whom, that )。此种情况下的关系代词可以省略;
This is just the man(whom/that) I want for the job. 这正是我要的做这份工作的人。
在本句中，先行词是the man;关系代词whom/that 引导定语从句，同时代替先行词在从句中担任动词want 的宾语。
Is he the manager (whom/that) you are looking for? 他是你在找的那位经理吗?
(3)当关系代词紧跟介词作介词宾语时，不能用that，也不能省略，
如：The book from which I got a lot of useful information was written by a famous scientist. 我从中得到许多有用信息的那本书是一位著名科学家写的。
Who is the boy with whom you were talking a moment ago. 你刚才和他说话的那个男孩是谁?
I know the young couple from whose house the music is coming. 但是当介词放在从句末尾时，作为介词宾语的关系代词可以用that 并且可以省略。
如上头两句可改为：
The book (that /which) I got a lot of information from was written by a famous scientist.
Who is the boy (that/whom) you were talking with a moment ago?
2.指物的关系代词which和that的用法：
(1)作主语
This is the instruction manual which/that tells you how to operate the computer. 这是那本教你如何操作计算机的说明手册。
(2)作宾语包括作介词宾馆。此种情况下的关系代词可以省略：
The chair (which /that) you broke yesterday is now being repaired. 你昨天弄坏的那把椅子现在正在修理。
The film (which/that) I saw last night was about a soldier who fought in WWII.
我昨天晚上看的那部电影是关于一个在二战中打过仗的士兵的。(本句有两个定语从句。)
This is the bike for which I paid $ 100. 这就是我花了100美元买的那辆自行车。
The car(which/that)he went in was a black Cadillac. 他坐在里面走了的那辆汽车是一辆黑色的卡迪拉克。
The accounts of the company, (which/that) I’ve been paying great attention to, are in balance. 我一直非常注意的公司账目，是保持平衡的。
3.whose 和of which 指代人或事物，作定语。of which 可用whose 代替;
The car whose lights (of which the lights/the lights of which) were all broken was my father’s. 那辆所有的灯都破了的汽车是我父亲的。
例：His house of which the windows (the windows of which /whose windows) were all broken was a depressing sight. 他那所有窗户都坏了的房子真是目不忍睹。
That is the book whose cover (of which the cover/the cover of which ) was broken. 这就是那本封皮破了的书。
4.关系代词的格应与它在从句中充当的成分一致。特别要注意插入语，
如：Peter is the one who everybody believes will fail to bring off the contract. Peter是那个人人都认为不能完成合同的人。(everybody believes 是插入语)
At the election I voted for the man whom I believed to be the most suitable. 在选举的时候我投了我认为最合适的那个人的票。
5.关系代词作从句的主语时，从句的动词必须和先行词的人称和数一致：
例：These are the operating instructions that/which are written in English. 这就是用英文写成的使用说明。
Are you staying at the white house which/that is newly completed and which /that has 15 bedrooms, 3 kitchens and 4 toilets? 你是住在那幢刚刚竣工、有15个卧室、3个病房和4个卫生间的白色房子里吗?
So far as I know, there are many VIPs who are going to attend the reception. 就我所知有很多达官贵人将出席这个招待会。
6.非限定性定语从句不用that，只用who(whose, whom)和which代表人和物;
例：Her brothers, both of whom work in America, ring her up every week. 她的兄弟们，两个人都在美国工作，每个星期都给她打电话。
The buses, most of which were already full, were surrounded by an angry crowd. 那些大多已经坐满了人的公共汽车被一群愤怒的人围着。
That tower block, which cost five million dollars to build, has been empty for five years. 那个塔楼空着已经5年了。建它花了500万美元。
Cricket, which I know very little about, is a very popular sport in England. 板球是英格兰非常流行的体育活动，我对它知之甚少。
The accounts of the company ,which I’ve been paying great attention to, are in balance. 公司的账目是保持平衡的。我一直非常注意这些账目。
7.关系副词(=介词 关系代词)：
关系副词
先行词
在从句中的作用
说明
when(=at/on/in/duringwhich)
时间名词
时间状语
非正式文体中，有时用that代替关系副词
例：I shall never forget the day when (=on which) we first met. 我永远也不会忘记我们第一次见面的那一天。
The rain came at a time when (=at which) it was not needed. 雨下得不是时候。
This is the computer where (=by/on which) he has stolen top-secret documents. 这就是他用来盗窃绝密文件的计算机。
Here is the place where (=at which) the murder took place. 这就是谋*发生的地方。
He didn’t give any reason why (=for which) I had been fired. 他没给任何解雇我的理由
This is the house in which (=where) my parents used to live. 这就是我父母以前住过的房子
注意事项：
(1)在非正式场合， that有时可用来代替关系副词或相当于关系副词的“介词 which”，而且经常全部省略，如：
In all the years that (=when/during which) I was at collage 在我读大学的那些年里
the reason that(=why/for which)he is not happy 他不高兴的理由
The direction(that)(=in which )the heavenly bodies move can’t be changed. 天体运行的方向是不可改变的。
He is unpopular because people don’t like the offensive way (that)(=in which) he talks. 他不受欢迎的原因是他说话的方式让人讨厌。
(2)是用关系代词还是用关系副词：
关系词(包括关系代词和关系副词)是学习英语定语从句的关键。用关系代词还是用关系副词，一要看关系词在从句当中作什么成分;二要看关系词所代表的是人、物、时间、地点还是原因;三要看所引导的是限定性定语从句还是非限定性定语从句。所以同样的先行词会有不同的关系词，这是因为关系词在从句当中担当的作用不同而决定的。
如：This is the room where/in which we’ll celebrate the New Year. 这是我们将要在里面庆贺新年的房间。(充当地点状语)
This is the room(that /which)we’ll celebrate the New Year in. 这是我们将要在里面庆贺新年的房间。(充当介词宾语，可省略。)
This is the room which /that will be used for the celebration of the New Year. 这是那个将要被用来庆贺新年的房间。(充当主语)
This is the room (which/that) we’ll use for the New Year dinner party. 这是我们将要用来举行新年晚宴的房间。(充当宾语，可省略。)
The reason (that /which) he had given was not sound enough. 他给的理由不够充分。(充当宾语，可省略)
The reason why/for which he had done that was not sound enough. 他做那件事的理由不够充分。(充当原因状语)
This is the house where she lives.这是她住的房子。
【比较：This is the house (that/which) she has bought. 这是她买的房子。This is the house that/which I’ve told you is extremely expensive.这就是我和你说过极其昂贵的那幢房子。】
I met him in the year when I was first in Xi’an. 我刚到西安的那年遇到了他。
That is the reason why he did not come that morning. 那就是那天上午他没来的原因。
(3)定语从句中的时态。如果主句是一般将来时或过去将来时，从句的动作与主句的同时发生，那么该从句要用一般现在时表示一般将来时、用一般过去时表示过去将来时。
例：Anyone who/that touches the wire will get an electric shock. 任何碰这根电线的人将受到电击。(不用will touch)
I would give her anything that she asked for. 她要什么我就给她什么。(不用would ask)
The first person who/that opens the door will get a shock. 第一个开门的人将被吓一跳。(不用will open)
There will be a special price for anybody who orders a suit in the next two weeks. 任何人在下两周内定做套装都将享受优惠价格。(不用will order)
但是，如果从句和主句的动作在将来不同的时间发生，则两部分都要用来将来时，
如：Those who will go abroad for training next year will start learning English tomorrow. 那些明年出国受训的人员，将从明天开始学习外语。
注：①先行词有最高级形容词修饰时，常用that，而不用which：
例：Edison was one of the greatest inventors that ever lived. 爱迪生是曾经有过的最伟大的发明家之一。
This is the best film that I’ve ever seen. 这是我曾经看过的最好的电影。
She was the greatest woman that/who has ever lived. 她是曾经有过的最伟大的女人。
②先行词有the same, the very, the first, the last, all, no, the only, much, little, none, any, every等时，常用that, 而不用which：
例：He was the first man that we saw in the village. 他是我们在那个村子里看到的第一个人。
There is little that is interesting. 没什么令人感兴趣。
I still remember the first time that we met. 我仍然记得我们第一次见面的时候。
I’ll do anything (that) I can to help you. 我将尽一切可能帮助你。
Everything that can be done has been done. 能做的一切都做了。
God bless this ship and all who sail in her. 愿上帝保佑此船和所有乘此船航行的人。
All that I can say is thank you very much. 我能说的是(千言万语变成一句话)：非常感谢你。
③当先行词既有人又有物时，用that，不用which，如：
We were deeply impressed by the workers and their working conditions that we had visited. 我们参观过的工人及他们的工作条件留下了深刻印象。
We listened to him talk about the men and books that interested him. 我们听他谈论他感兴趣的人物和书籍。
④在same和such之后，定语从句用as引导，如：
Let’s discuss only such questions as concern us. 让我们只讨论与我们有关的问题。
I’ve never heard such stories as he tells. 我从来没听说过他讲的这种故事。
I shall be surprised if he does this in the same way as I do. 如果他做这件事的方法和我一样，那就奇怪了。
She works in the same office as I do. 她和我在同一个办公室工作。
She wears the same kind of clothes as her sister does. 她姐妹俩穿同样的衣服。
He’s wearing the same dress as he wore at Mary’s wedding. 他穿着与他在Mary的婚礼上穿的一样的衣服。
This is the same watch as I have lost. 这块表和我丢的那块一样。
I’ve never seen such kind of people as they are. 我从来没见过像他们这样的人。
I’ve never seen such kind people as they are. 我从来没见过象他们这样厚道的人。
I want the same shirt as my friend’s. 我要一件跟我朋友一样的衬衫。
Such machines as are used in our workshop are made in china. 我们车间使用的这种机器是中国制造的。
但是，如果从句和主句的动作在将来不同的时间发生，则两部分都要用来将来时，
注：④在same和such之后，定语从句用as引导，偶尔，the same 后面也用that，如：
He’s wearing the same suit that he wore at Mary’s wedding. 他穿着与他在Mary的婚礼上穿的一样的衣服。
She works in the same office that I do. 她和我在同一个办公室工作。
This is the same watch that I have lost. 这块表和我丢的那块一样。
as 引导非限定性定语从句即可放在主句之前，也可放在主句之后，用来修饰整个句子。当as在从句中作主语时，后面常接下列句型。如：as is known, as is said, as is reported as is announced 等。例如：
As we all know, Mr. Wang is a good teacher.
As is known to all, the earth revolves round the sun.
He is tired, as you can see.
As I expected, he didn’t believe me.
As 引导非限定性定语从句时与which的区别：当主句和从句语义一致时，用as;反之，用which。如：
He made a long speech, as was expected.
He made a long speech, which was unexpected.
Tom drinks a lot every day, which his wife doesn’t like at all.
(3)但是，如果从句和主句的动作在将来不同的时间发生，则两部分都要用来将来时，注：⑤在“介词 关系代词”的结构中，也可用复杂介词，如：by means of (用，依靠)，as a result of (作为结果)等。例：
I have three children, one daughter and two sons, all of whom graduated from the same university. 我有三个孩子：一个女儿、两个儿子，他们都毕业于同一所大学。
The police, in whom I have great confidence, are trying to find out who did it. 我对警察有极大的信心，他们正在努力寻找是谁做的这件事。
This is the part of the river in which I like to swim. (in which=where) 我喜欢在这条河里面游泳，这就是(我喜欢游的)那个地方。
The man from whom you bought the house is my uncle. 你从他那里买下房子的那个人是我叔叔。
This is the desk by means of which he jumped over the wall. 这就是他用来跳过墙去的那张桌子。
She was running a fever, as a result of which she failed in the exam. 她当时正发烧，所以考试失败了。
He is the man from whose house the picture was stolen. 他就是那个家里的画被偷了的人。
注：⑥一个先行词后面可以跟一个以上的定语从句，这种现象叫双重关系从句。例：
Here are some words which are often used but which are very confusing. 这里有些常用但非常混乱的词。
He is the only person that I can find who is able to solve the problem. 他是我能找到的唯一解决这个问题的人。
