一、概述
所谓定语从句，就是指在主从复合句用作定语的从句。定语从句通常修饰名词或代词，对它进行限制、描绘和说明。受定语从句修饰的词语叫先行词，引导定语从句的词语叫关系词。关系词按其性质又分关系代词和关系副词。关系词不仅引导定语从句，同时还在定语从句充当一定的句子成分：
The girl who spoke is my best friend. 讲话的姑娘是我最好的朋友。
此句中，who spoke是由关系代词who引导的定语从句，用以修饰先行词the girl，同时who 在定语从句中用作主语。
This is the town where I was born. 这就是我出生的城市。
此句中，where I was born是由关系副词where引导的定语从句，用以修饰先行词the town，同时where在定语从句中用作状语。
二、考点归纳
考点1 考查关系代词的判断与用法
在初中英语中，应该掌握的关系代词不多，主要有that, who, whom, whose, which，其中who和whom 只用于指人，which只用于指事物，whose和 that既可于指人也可用于指物。各个关系代词在定语从句中的用法是：that可用作主语或宾语，who用作主语，whom用作宾语，whose用作定语，which用作主语或宾语。选用关系代词有两个技巧：
一看先行词的意义：指人用who, whom, whose, that；指物用which, that, whose。
二看关系词的句法功能：作主语用that, which, who等；作宾语用whom, that, which等。
A plane is a machine that can fly. 飞机是一种能飞行的机器。(that指物，在从句中用作主语)
The man who lives in that house is my uncle. 住在那座房子里的人是我叔叔。(who指人，在从句中作主语)
The house whose windows are broken is empty. 破了窗户的那座房子是空的。(whose指物，在从句中作定语)
There are some students whose questions I can’t answer. 有些学生提出的问题我回答不了。(whose指人，在从句中作定语)
值得注意的是，what不能用作关系代词，所以不能用于引导定语从句；另外，人称代词he, she, we, they, it等也不能用作关系代词，也不能引导定语从句。
【考例1】The girl ________ I just talked with is Ben’s mother. (四川成都中考题)
A. whom B. which C. she D. what
【分析】答案选A。由于先行词为指人的名词，所以引导定语从句的关系代词不能用which，故可排除B；而what和she不是关系代词，不能引导定语从句，故可排除C和D。
【考例2】The pen ________ you are looking for is under the desk. (湖南邵阳中考题)
A. who B. whose C. that D. what
【分析】答案选C。因为关系代词在定语从句中指物且用作宾语，所以不能选A；又因为空格后没有名词，所以不宜选B；而what不能用作关系代词，不能引导定语从句，所以排除D。
【考例3】I don’t know the teacher ________ is talking with Miss Wang. (山东淄博中考题)
A. what B. whom C. which D. who
【分析】答案选D。由于先行词为指人的名词，所以引导定语从句的关系代词不能用which，故可排除C；而what不是关系代词，不能引导定语从句，所以排除A；再通过分析定语从句的句子成分可知，该定语从句缺主语，所以只能选主格who，不能选whom。
考点2 考查关系代词的省略问题
在通常情况下，关系代词是不能省略的。但有一种例句，就是当关系代词作宾语时，它可以省略（不管是指人还是指物）。如：
Is there anything (which) you wanted? 想要什么东西吗?
Who is the man (that / who / whom) you were talking to? 刚才和你讲话的人是谁?
但是，当关系代词在定语从句中用作主语时，是绝不能省略的。如：
他就是住在隔壁的那个人。
误：He is the man lives next door.
正：He is the man who lives next door.
另外，即使是用作宾语，如果是紧跟在介词后也不能省略。如：
这就是他向他们说过的那所房子。
误：It was the house about he had told them.
正：It was the house about which he had told them.
【考例1】This is the novel ________ is written by Guo Jingming. (山东德州中考题)
A. who B. what C. that D. 不填
【分析】答案选C。由于what不是关系代词，不能引导定语从句，故可排除B；又由于先行词novel指物，所以不能选指人的who，故可排除A；又因为关系代词在定语从句中用作主语，所以不能省略，故可排除D。
【考例2】The skirt ________ is made of silk is very expensive. I can’t afford it. (湖北孝感中考题)
A. what B. 不填 C. that D. it (www.yygrammar.com)
【分析】答案选C。由于what和it不能用作关系代词，不能引导定语从句，所以排除A和D；又因为关系代词在定语从句中用作主语，所以不能省略，故选C。
考点3 考查关系代词that与which的区别
两者均可用于指物，通常可互换。如：
That is the house that [which] we built. 这就是我们盖的房子。
She was not in the train which [that] arrived just now. 她不在刚到的那列火车上。
但是，that可以指人，而which不能指人。如：
Who is the man that you were talking to? 刚才和你讲话的人是谁?
She is the girl that you saw in school. 她就是你在学校见到的那个女孩。
另外，在以下情况，通常用that引导定语从句：
1. 当先行词是every(thing), any(thing), no(thing) 等不定代词或受其修饰时。如：
Take anything that you want. 你想要什么，就拿什么。
Everything that can be done must be done. 凡能做的事都必须做。
2. 当先行词受the very, the only, the same 等修饰时。如：
This is the only example that I know. 我知道的例子只有这一个。
This is the very watch that I lost yesterday. 这就是我昨天不见了的表。
3. 当先行词有形容词最高级或序数词(包括last, next等)等修饰时。如：
It was the largest map that I ever saw. 那是我所看见过的最大的地图。
This is the best picture that he has ever painted. 这是他所画的画当中最好的一幅。
4. 当先行词是一个既指人又指物的并列词组时。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。
【考例】I’ve found some pictures of the most interesting places ________ you can visit during the winter holidays. (山东烟台中考题)
A. where B. which C. what D. that
【分析】答案选D。由于what不是关系代词，不能引导定语从句，所以排除C；通过分析定语从句的句子结构可知，该定语从句的谓语动词visit缺宾语，由此可排除关系副词where（因为关系副词只能用作状语）；另外，由于先行词受到最高级的修饰，故应选关系代词that，而不选which。
考点4 考查关系代词whose的用法
用作关系代词whose既可用于指人，也可用于指物，它在定语从句通常用作定语。如：
He’s written a book whose name I’ve forgotten. 他写了一本书，书名我给忘了。
I’d like a room whose window looks out over the sea. 我想要一个窗户面临大海的房间。
There are some students whose questions I can’t answer. 有些学生提出的问题我回答不了。
I saw a girl whose hair came down to her waist. 我看见一个女孩子，她的头发长得垂到腰部。
【考例1】I like the teacher ________ classes are very interesting and creative. (甘肃兰州中考题)
A. which B. who C. what D. whose
【分析】答案选D。由于关系代词在定语从句中用作定语，修饰名词classes，所以只能选whose。又如：The girl whose work got the prize is the youngest in her class. 作品获奖的女孩是她班上年纪最小的。
【考例2】We know Jackie Chan ________ movies are very popular with the young. (湖北恩施中考题)
A. whose B. that C. who D. which(http://ask.yygrammar.com/)
【分析】答案选A。空格后有名词movies，可见关系代词在定语从句是用作定语，故只能选whose，即选A。
考点5 考查关系副词的用法
英语中用于引导定语从句的关系副词只有三个，它们是when, where和why。三者的区别是：when用于指时间，where用于指地点，why用于指原因，同时它们在引导定语从句的同时也在定语从句中充当状语（不能充当主语或宾语）。如：
1980 was the year when he was born. 1980是他的出生年。
This is the room where he lived. 这就是他曾住过的房间。
These are the reasons why we do it. 这些就是我们这样做的理由。
注意，当先行词为表时间、地点或原因的名词时，不要盲目地选用关系副词，同时还要考虑其后定语从句的句子成分是否完整――若完整，则可考虑选用关系副词；若不完整（比如缺主语或宾语），则不能选关系副词，而应考虑选用关系代词。
【考例】―What do you think of the book A Haw Tree written by a woman writer?
―It reminds me of the days ________ I spent in the countryside.(湖北宜昌中考题)
A. when B. that C. who D. where
【分析】答案选B。虽然先行词为表示时间的days，但这里不能选关系副词when，因为其后的定语从句谓语spent后没有宾语，这说明空格处应填一个关系代词，并且是一个指事物的关系代词，显然只能选B。
考点6 将定语从句与其他知识点综合考查
这类考题比较灵活，同学们做题时要注意联系相关知识点，进行综合分析，选出最佳答案。下面略举两列加以说明：
【考例1】―Is everything ________ we need to do ________?
―Yes. You needn’t worry about it. (辽宁锦州中考题)
A. which; has done B. which; doing C. that; has done D. that; done
【分析】答案选D。用于修饰everything的定语从句通常要用that，而不用which，故可排除A和B；又因为everything与do之间为被动关系，故用被动语态，即选D。
【考例2】―Do you know the boy ________ is sitting next to Peter?
―Yes. He is Peter’s friend. They are celebrating this ________ birthday. (广东深圳中考题)
A. who, ninth B. that, nineth C. /, nineth D. which, ninth
【分析】答案选A。由于先行词为指人的名词，所以引导定语从句的关系代词不能用which，故可排除D；又因为nine的序数词是ninth，而不是nineth，故可排除B和C。
三、易错陷阱
陷阱1 误认为关系代词that只用于指物
有的同学认为，关系代词只用于指物，不用于指人，这是误解。其实，作为关系代词的that，它既可以指人也可以指物，并且在指人时两者通常可以换用。如：
The man whom (=that) I saw told me to come here. 我见到的人让我到这里来。
但是，当先行词是一既指人又指物的并列词组时，通常要用that，不用who。如：
He made a speech on the men and things that he’d seen abroad. 他就在国外见到的人和事作了报告。
陷阱2 误认为关系代词whose只用于指人
用作关系代词的whose 与关系代词who（只用于指人，作主语）和whom（只用于指人，作宾语）不一样，它不仅可以指人也可以指物，在定语从句中通常用作定语。如：
He is the man whose car was stolen. 他就是汽车被窃的人。
The boys whose names were called stood up. 叫到名字的男孩们站了起来。
It was an island whose name I have forgotten. 这是一座岛，名字我忘了。
Can you see the mountain whose top is covered with snow? 你看得见山顶上覆盖着雪的那座山吗?
陷阱3 将what误用作关系代词来引导定语从句
what不是关系代词，不能用于引导定语从句。但是，what可以引导宾语从句，并且有时可以包含一个定语从句。如：
他把一切都给了我。
正：He gave me what he had.
正：He gave me everything that he had.
误：He gave me everything what he had.
这就是你要的东西。
正：This is what you want.
正：This is the thing that you want.
误：This is the thing what you want.
以上实例告诉我们，what 有时相当于“先行词+关系代词”，同时这也告诉我们，这样用的what前不能再有先行词（因为what不是关系代词，不能引导定语从句）。
陷阱4 在定语从句中误加人称代词
前面我们讲到，关系代词在定语从句中主要用作主语或宾语，所以在做有关定语从句的试题时，考生千万不要在定语从句中重复使用与先行词指代相同的人称代词。如：
我们昨晚看的电影很精彩。
误：The film that we saw it last night was wonderful.
正：The film that we saw last night was wonderful.
刚才同你讲话的那个人是谁?
误：Who’s the man that you just talked to him?
正：Who’s the man that you just talked to?(http://ask.yygrammar.com/)
你昨天借给我的书很有趣。
误：The book which you lent it me yesterday was very interesting.
正：The book which you lent me yesterday was very interesting.
【训练吧】
选择最佳答案填空：
1. Sorry, we don’t have the coat ________ you need.
A. what B. who C. whom D. which
2. Ten months has passed, but Chinese people still remember those exciting days ________ they spent during the Beijing 2008 Olympic Games.
A. that B. who C. when D. where
3. Jim dislikes people ________ talk much but never do anything.
A. whom B. when C. whose D. who
4. It’s time to say goodbye to my school. I’ll always remember the people ________ have helped me.
A. who B. what C. which D. where
5. I love people ________ are friendly to others.
A. which B. whose C. what D. who
6. ―Could you tell me something about Zheng He?
―Sure. He was a Ming Dynasty explorer ________ the Chinese people are proud of?
A. which B. whose C. whom D. where
7. ―What are you looking for?
―I’m looking for the pen ________ I bought yesterday.
A. who B. which C. whose D. it
8. ―What kind of music do you like?
―I like music ________ I can sing along with.(www.yygrammar.com)
A. who B. where C. that D. when
9. This is the most beautiful picture ________ I have seen.
A. that B. which C. whose D. what
10. Many young people love the songs ________ have great lyrics.
A. who B. those C. which D. what
11. Do you know the man ________ is sitting behind
A. what B. which C. who D. whom
12. Is this the train ________ stops at
A. what B. that C. when D. why
13. The watch ________ you gave me keeps perfect time.
A. that B. what C. who D. how
14. The people ________ called yesterday want to buy the house.
A. who B. which C. whom D. what
15. Which Mr Smith do you mean―the one ________ teaches history or the one ________ teaches music?
A. who, who B. which, which C. what, what D. he, he
16. The woman ________B________ umbrella you took is very angry about it.
A. who B. whose C. her D. which
【答案点拨吧】
1. 答案选D。由于先行词为指物的名词，所以引导定语从句的关系代词不能用who和whom，故可排除B和C；而what不是关系代词，不能引导定语从句，所以排除A。
2. 答案选A。虽然先行词是表示时间的days，但由于定语从句中的谓语动词spent缺宾语，故先行词不能选关系副词when，而应选关系代词that。至于who（用于指人）和where（用于指地方）均不合题目要求。
3. 答案选D。由于先行词为指人的名词，同时关系代词在定语从句中用作主语， 故只能选指人的主格关系代词，四个选项中只有who符合要求。
4. 答案选A。由于先行词为指人的名词，所以引导定语从句的关系代词不能用which，故可排除C；而what不是关系代词，不能引导定语从句，故可排除B；由于where为关系副词，它此引导定语从句时，只能在从句中用作状语，不能用作主语。
5. 答案选A。由于先行词为指人的名词，所以引导定语从句的关系代词不能用which，故可排除A；而what不是关系代词，不能引导定语从句，故可排除C；由于关系代词在定语从句中有作主语，不是用作定语，故用who，不用whose。
6. 答案选C。由于先行词指人，故其后引导定语从句的关系词不能是which；而where只用于表示地点，也可排除；而关系代词whose主要用于名词前作定语，而空格后没有所修饰的名词，故也可排除。
7. 答案选B。由于it不是关系代词，不能引导定语从句，所以排除D；又因为先行词pen指物，不指人，故排除A；分析定语从句的句子结构可知，其谓语动词bought缺宾语，故选which。
8. 答案选C。由于music指事，不指人，故不能选who，排除A；又因为空格处所填关系代词用作介词with的宾语，所以不能选只用作状语的关系副词when和where，故排除B和D。
9. 答案选A。由于关系代词在定语从句中充当宾语，故只能选that和which，排除选项C；而what不是关系代词，不能引导定语从句，所以也被排除。另外，先行词受形容词最高级，所以其后的定语从句要用that来引导，故选A。
10. 答案选C。因先行词是the songs，指物，故用关系代词which，它在从句中作主语。(www.yygrammar.com)
11. 答案选C。因先行词是the man，指人，并在从句中作主语，故只能用关系代词who，即答案选C。
12. 答案选B。由于定语从句 ________ stops at Cambridge的句子结构不完整，句子缺主语，故可排除只能用作状语的C和D；而what不是关系词，不能引导定语从句，故可排除A。
13. 答案选A。由于what和how都不是关系词，不能引导定语从句，故可排除B和D；who只用于指人，不用于指事物，故可排除C。that在此引导定语从句，且在定语从句用作宾语，也可省略。
14. 答案选A。当先行词指人时，要用who来引导定语从句，不能用which，故可排除B；而whom虽然可用于指人，但它是宾格，只用作宾语，不能用作主语，故也被排除；至于what，它根本不是关系代词，不能引导定语从句。
15. 答案选A。当先行词指人时，要用who来引导定语从句，不能用which。而选项C和D均不是关系代词，不能引导定语从句。
16. 答案选D。引导定语从句且在定语从句中作定语时，有两个关系代词可以用，一个是whose，一个是which。其中whose相当于one’s的意义，which相当于this或that的意思。