关系代词的概念：

英语中的关系代词有who, whom, whose, that, which, 它们是用来引导定语从句的。关系代词既代表定语从句所修饰的词，又在其所引导的从句中承担一个成分，如主语、宾语、表语、或定语。
如：This is the man who saved your son. (who在从句中作主语，先行词是man） 
        The man whom I met yesterday is Jim.
        A child whose parents are dead is an orphan.
        He wants a room whose window looks out over the sea.

1、关系代词用来引导定语从句。它代表先行词，同时在从句中作一定的句子成分，例如：
   The girl to whom I spoke is my cousin.　跟我讲话的姑娘是我表妹。（该句中whom
   既代表先行词the girl，又在从句中作介词to的宾语。）
2、关系代词有主格，宾格和属格之分，并有指人与指物之分。在限定性定语从句中，that
   可指人也可指物， 见表：

	指人	指物	指人或物
主格	who	which	that
宾格	whom	that	that
属格	whose	whose/of which	of which/whose

例如：
　 This is the pencil whose point is broken. 这就是那个折了尖的铅笔。
　 (whose 指物，在限定性定语从句中作定语)
　 He came back for the book which he had forgotten.　他回来取他丢下的书。
　 （which指物，在限定性定语从句中作宾语，可以省略） 
★关系代词的用法
1、关系代词的句法功能
1）关系代词在句中作主语
    例如：I prefer music that/which has great lyrics
2）关系代词在句中作宾语
    例如：I like music that I can sing along with.
3）关系代词在句中作表语
    例如：The house is not the one (that) it used to be.
2、关系代词在从句中作名词的定语
    例如：Is she the teacher whose hair is very short?
3、关系代词的用法
1）who和whom的用法：二者都用于指人。Who在定语从句中作主语、宾语，whom
    在定语从句中作宾语。Whom在从句中能坐介词的宾语，而who则不能。
    例如：I happened to meet the professor (who/whom) I got to know at a party
             in the shopping center yesterday.
2）whose的用法：一般指人，有时也指物。在定语从句中作定语。
    例如：I have got a friend whose brother is training for the Olymoics.
3）which的用法：一般指物，在定语从句中作主语、宾语、偶尔作定语。
    例如：The photo which we liked best was taken by Zhao Min.
4）that的用法：指人或物，指人时可与who、whom互换，指物时可与that互换。在
    从句中可作主语、宾语，还可作表语。
    例如：It is a book (that/which) no one really likes.
4、用who不用that的情况
1）先行词是指人的不定代词时
    例如：Congratulations to our winners and thanks to everyone who entered
             the competitions. 
2）先行词指人并含有较长的后置定语或在被分割的定语从句中时
   例如：The boy was crying hard who lost his way while looking for his mother.
3）用在there be结构中。
   例如：There is a young man who wants to see you.
4）避免重复或引起歧义。
   例如：The man that spoke at the meeting is our new headmaster who has just come from Shanghan.
5）当先行词是I, you, he, they等时（常用语谚语之中）。
   例如：He who plays with fire gets burned.
6）先行词如是指成员的集体名词，关系代词也用who。
   例如：The family, who live upstairs, are fond of music.
7）先行词如是拟人化名词，关系代词也可用who。
   例如：You will see the worker ants,who gather food for themselves and for all the others.
8）先行词指特定的人时，关系代词多用who，不指特定的人时多用that。
   例如：The aunt who came to see us last week is my father’s sister.
         People that have not been properly trained can’t do this kind of qork.
5、在以下情况中，关系代词用that
1）先行词为all, little, few, none 及some-, any-, no-与thing所组成的复合单词时，只能用that。
   例如：There is nothing that will stop us making progress.
2）先行词前有only, some, any等形容词修饰时，只能用that。
   例如：This is the only problem that we can’t work out.
3）先行词前由形容词的最高级或序数词修饰时，只能用that。
   例如：This is the most interesting book that I have ever read.
4）先行词同时包括人和物时，只能用他和她， 
   例如：Lu Xun and his works that we are familiar with are considered great.
6、只能用which不能用that的情形
1）当非限制性定语从句中的先行词指物时，只能用which 
   例如：The pencil-case, which I bought last week, is missing.
2）关系代词前面有介词时，只能用which
    例如：The tree under which we used to take a rest has been cut down.
3）先行词本身就是that时
    例如：I don’t like that which he did.
7、介词与关系代词
1）与关系代词搭配的介词的确定
   （1）依据定语从句中动词所需要的某种习惯搭配来确定。
        I bought a great many books, on which I spent all my money that I saved.
（2）依据先行词的某种下滚搭配来确定。 
     I'll never forget the time during which I spent my childhood in the country.
（3）根据所表达的意思确定。 
     The colorless gas without which we can’t live is called oxygen.
（4）在英语中有时为了强调某一名词，关系代词前也加上介词。 
     Here is the money with which to buy a piano.
2、关系代词作介词的宾语时，介词的位置
1）关系代词whom，which在从句中作介词宾语时，可以和介词一起放在先行词和从句之间。为了
   使关系代词紧跟它所修饰的词，也可以把介词放在从句中有关动词的后面。
   The old man whom the nurses are looking after is very well now.
2）含有介词的短语动词一般不拆开，介词仍放在动词的后面。
   Is this the watch which he is looking for?
3）关系代词that在从句中作介词宾语时，介词不能放在它的前面，只能放在从句中有关动词的后面。
   The city that she lives in is very far away?
4）关系代词whose也可以在从句中与它所修饰的名词一起作介词宾语。
   The boss in whose company my father worked is a very kind person.
3、“名词/数词/代词/介词+关系代词” 结构常见的形式有：名词one/two/some/many/the+最高  
    级…+of+which/whom。
    I have two sisters, both of whom are teachers.

关系代词知识体系：

 

关系代词用法：

1、that与which的用法区别：
      两者都可指物，常可互换。其区别主要在于：
（1）引导非限制性定语从句时，通常要用which：
如：She received an invitation from her boss, which came as a surprise. 她收到了老板的邀请，这是她意想不到的。
（2）直接放在介词后作宾语时，通常要用which：
如：The tool with which he is working is called a hammer. 他干活用的那个工具叫做锤子。
（3）当先行词是下列不定代词或被它们修饰时much, little, none, all, few, every(thing), any(thing), no(thing)等时，通常用that：
如：There was little that the enemy could do but surrender. 敌人无法,只有投降了。
        All[Everything] that can be done must be done. 凡能做的事都必须做。
（4）当先行词有the very, the only, the same等修饰时，通常用that：
如：This is the only example that I know. 我知道的例子只有这一个。
        Those are the very words that he used. 那是他的原话。
（5）当先行词有形容词最高级或序数词（包括last, next等）等修饰时，通常用that：
如：This is the best dictionary that I've ever used. 这是我用过的最好的词典。
        The first thing that you should do is to work out a plan. 你应该做的第一件事是订个计划。 
（6）当关系代词在定语从句中用作表语时，通常用that：
如：China is not the country(that) it was. 中国已不是过去的中国了。
（7）当先行词是一个既指人又指物的并列词组时，通常用that：
如：They talked about the persons and things that most impressed them. 他们谈论了使他们印象最深的人和事。
（8）当要避免重复时：
如：Which is the course that we are to take? 我们选哪门课程？

2、that与who的用法区别：
（1）两者均可指人，有时可互换：
如：All that[who] heard him were delighted. 所有听了他讲话的人都很高兴。    
        Have you met anybody that[who] has been to Paris? 你遇见过到过巴黎的人吗?
        He is the only one among us that[who] knows Russian. 他是我们中间唯一懂俄语的人。
（2）但是在下列情况，通常要用that： 
   ①当先行词是一个既指人又指物的并列词组时： 
如：I made a speech on the men and things that I had seen abroad. 我就我在国外所见到的人和事作了报告。
   ②当先行词是who时(为避免重复)：
如：Who was it that won the World Cup in1982? 谁赢得了1982年的世界杯？
   ③当关系代词在定语从句中作表语时(可省略)：
如：Tom is not the boy(that) he was. 汤姆这孩子已不是以前那个样子了。

关系代词用法拓展：

1、as与which的用法区别：
(1)引导限制性定语从句时，在such,as,thesame后只能用as，其他情况用which：
如：I never heard such stories as he tells. 我从未听过他讲那样的故事。
        It's the same story as I heard yesterday. 这故事跟我昨天听到的一样。
        This is the photo which shows my house. 这张照片拍的是我的住宅。
(2)引导非限制性定语从句时，有时两者可互换：
如：I live a long way from work, as [which] you know. 我住得离工作单位很远，这你是知道的。
(3)但在，在以下情况引导非限制性定语从句时，两者不可换用：
①当从句位于主句前面时，只用as：
如：As is known to everybody, the moon travels round the earth once every month. 月球每月绕地球转一周，这是每个人都清楚的。
②as引导的非限制性定语从句应与主句在意义上和谐一致，which无此限制：
如：He went abroad, as[which] was expected. 他出国了，这是大家预料到的。
        He went abroad, which was unexpected. 他出国了，这让大家感到很意外。(不用as)
③as引导非限制性定语从句时，先行词通常不能是主句中某个具体的词，而应是整个句子、整个短语或某个短语推断出来的概念，而which则无此限制：
如：The river, which flows through London, is called the Thames. 这条流经伦敦的河叫泰晤士河。(不用as)
④当as引导非限制性定语从句作主语时，其谓语通常应是连系动词，而不宜是其他动词，而which则无此限制：
如：She has married again, as[which] seemed natural. 她又结婚了，这似乎很自常。
        She has married again, which delighted us.她又结婚了，这使我们很高兴。(不用as)

2、who与whom的用法区别：
两者均只用于人，从理论上说，who为主格，whom为宾格：
如：Where's the girl who sells the tickets? 卖票的女孩在哪里？
        The author whom you criticized in your view has written a letter in reply. 你在评论中批评的那个作者已写了一封回信。
但实际上，除非在正式文体中，宾格关系代词whom往往省略不用，或用who或that代之：
如：The man(that, who, whom) you met just now is called Jim. 你刚遇见的那个人叫吉姆。
不过，在以下几种情况值得注意：
(1)直接跟在介词后面作宾语时，只能用whom，而且不能省略：
如：She brought with her three friends, none of whom I had ever met before. 她带了3个朋友来，我以前都没见过。
(2)引导非限制性定语从句且作宾语时，who和whom均可用，但以用whom为佳，此时也不能省略：
如：This is Jack, who[whom] you haven't met before. 这是杰克，你以前没见过。