定语从句一、定义：在复合句中，修饰名词或代词的从句叫定语从句，被修饰的名词或代词叫先行词，引导定语从句的引导词分为：关系代词who, whom, whose, which, that等，和关系副词where, when, why等，关系代词和关系副词在定语从句中担任句子成份，不可省略。
1.由who引导的定语从句中，who用作主语，如：This is the boy who often helps me.2.由whom引导的定语从句中，whom用作宾语，如：The man whom you are waiting for has gone home.3.由whose引导的定语从句中，whose用作定语，如：Do you know the girl whose skirt is white?4.由which引导的定语从句中，which用作主语或谓语动词的宾语或介词的宾语。
如：The room in which there is a machine is a workshop（车间）.The river which is in front of my house is very clean.This is the pen which you want.注意：(1)whom, which用作介词宾语时，介词可放在whom、which之前，也可放在从句原来的位置上；但在含有介词的动词固定词组中，介词只能放在原来的位置上。
如：He is the very person whom we must take good care of.(2)引导非限制性定语从句时，必须用关系代词which，不用that。
如：I have lost my bag, which I like very much.(3)关系代词在句中作主语时，从句的谓语动词的人称和数必须和先行词保持一致。
5.由that引导的定语从句中，that可以指人或物，在从句中作主语或谓语动词的宾语，但不能放在介词后面作介词宾语，即介词后只能用w hich,不能用that.如：The book that I bought yesterday was written by Lu Xun.注意：在下面几种情况下必须用that引导定语从句。
(1)先行词是不定代词something, nothing, anything，everything等,如：All that we have to do is to practise English.(2)先行词被序数词或形容词最高级所修饰，如：The first letter that I got from him will be kept in my case .(3)先行词被all, any, every, each, few, little, no, some等修饰，如：I have eaten up all the food that you gave me .(4)先行词被the only, the very, the same, the last修饰时,如:H e is the only person that I want to talk with.(5)先行词既有人又有物时，如:They talk about persons and things that they met .(6)当句中已有who时,为避免重复，如： Who is the man that is giving us the class?6.由when, where, why引导的定语从句，如: I don't know the reason why he was late.This is the place where we have lived for 5 years.I'l l never forget the day when I met Mr Li for the first time.注意：先行词是表示地点时，如果从句的谓语动词是及物的，就用that(which)，如果从句的谓语动词是不及物的，就用where引导。
This is the house which /that he has lived in for 15 years.(where he has lived for 15 year.)7、限制性定语从句和非限制性定语从句：（1）限制性定语从句是句中不可缺少的组成部分，主句和从句之间不用逗号隔开，引导限制性定语从句的关系代词有：who,whom,whose,which,of which等，这些关系代词都不可省。
（2）非限制性定语从句是对主句先行词的补充说明，没有这种从句，不影响主句意思的完整性，一般用逗号将其与主句隔开，关系代词用which,不用that;指人时可用who.Eg: I have two brothers, who both are both students.8、如何简化定于从句（1）定语从句简化为形容词或形容词短语作后置定语。
Eg:My grandfather lives in a village which is far away from here.→My grandfather lives in a village far away from here.(2)定语从句简化为现在分词或现在分词短语作前置或后置定语。
Eg:The man who is standing under the tree is our English teacher.→The man standing under the tree is our English teacher.I saw the house that was burning（燃烧）at that time.→ I saw the house burning at that time.(3)定语从句简化为过去分词短语作后置定语。
Eg:I like to eat the cakes which ar e made by my mother.→I like to eat the cakes made by my mother.(4)定语从句简化为不定式作后置定语。
Eg:She is always the first person that comes to school .主动→She is always the first person to come to school .The report which will be given tomorrow is very importance for us.被动→The report to be given t omorrow is very importance for us.(5)定语从句简化为what从句。
Eg:I couldn’t remember the words that he said .I couldn’t remember what he said .练习、I单选题1. The silk _______ is made in Hangzhou sells well.A. thatB.whoC. whatD. /2. The man_______today left this message for you.A.calledB.has calledC.whom calledD.who called3. Do you live near the building ______color is yellow?A. thatB.whichC.whoseD. its4. He helped his father on the farm ______they lived.A. whichB.thatC.whenD. where5. I’m one of the boys_____never late for school.A.that isB.who isC.who areD.who am6. All_____should be done has been done.A.whatB.whichC.thatD.whatever7. Jack told me everything _______he knew about it.A. whatB.thatC.whichD.who8. My father works in the factory ______this type of truck is made.A.in whereB.in whichC.from whichD.of which9. The school_______we visited last week was built in 1956.A./B.whereC.thatD.both A and C10. This is one of the best films_______I have ever seen.A.whichB.thatC.of whichD.of that11. In fact the Swede(瑞典人） did not understand the three questions_______were asked in French.A.whereB.whoC.in whichD.which12. He paid the boy $10 for washing ten windows, most of ______ hadn’t been cleaned for at least a year.A.theseB.thoseC.thatD.which13. His parents wouldn’t let him play with anyone ________family was poor.A.of whomB.whomC.of whoseD.whose14. All_______is needed is a wonderful meal.A.the thingB.thatC.whatD.which15. In the dark street ,there wasn’t a single person _____she could turn for help.A.thatB.whoC.from whomD.to whom16. She heard a terrible noise,______brought her heart into her mouth.A.itB.whichC.thisD.that17. -Do you know the man ______is talking with your father？-Y es，he‘s our headmaster.A. heB. whoC. whichD. whom18. Is this the river _____I can swim？A. whichB. in whichC. thatD. the one19. This is the best hotel in the city _____I know.A. whereB. whichC. thatD. it20. Can you lend me the dictionary ______the other day？A. that you boughtB. you bought itC. that you bought itD. which you bought it21. Anyone ______with what I said may put up you hands.A. which agreesB. who agreeC. who agreesD. which agree22. My watch is not the only thing ______ is missing.A. thatB. itC. whichD. who23. The man ______coat is black is waiting at the gateA. who’ sB. whoseC. thatD. of which.24. The girl ______ is reading under the tree _____my sister.A. which； isB. whom； wasC. who； isD. who； was25. I love places ______the people are really friendly.A. thatB. whichC. whereD. who26. The world ______ is made up of matter.A. in that we liveB. on which we liveC. where we live inD. we live inII 用适当的关系词填空：1) I’ll never for get the day on ________ they met for the very first time last summer.2) This is the place _________ he so often mentioned(提及、谈论）to me.3) The only thing ________ interested him was that he could do anything _________ he wanted to.4) “What a scientist! What a wonderful invention!” he talked excitedly about Bill Gates and his Microsoft Comp-any _________ is now a focus (焦点) of newspapers and television.5) He is old, ________ fact is important in this case.6) Finally, the thief handed everything __________ he had stolen.7) W e talked about the things and persons _________ we saw then.8) W ith _________ were you talking?9) This is the very present __________ my mother gave me.10) Which is the bike __________ is made in Shanghai?11) I think this is the most beautiful dress ______ I own.12) Those _______ want to buy the house may sign their names(签名）first.13) My sister, __________ you met in Guangzhou, has bought a new car.14)That’s the way _______ they work.。