定语从句（初中）在复合句中，修饰某一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，定语从句一般放在先行词的后面。
二、定语从句的关系词引导定语从句的关系词有关系代词和关系副词，常见的关系代词包括that，which，who（宾格whom，所有格whose）等，关系副词包括where，when，why等。
关系代词和关系副词放在先行词及定语从句之间起连接作用，同时又作定语从句的重要成分。
三、定语从句的分类根据定语从句与先行词的关系，定语从句可分为限制性定语从句及非限制性定语从句。
限制性定语从句紧跟先行词，主句与从句不用逗号分开，从句不可省去，非限制性定语从句主句与从句之间有逗号分开，起补充说明作用，如省去，意思仍完整。
四、关系代词的用法1. that 既可以用于指人，也可以用于指物。
在从句中作主语或宾语。
例如：Mary likes music that is quiet and gentle.（that作主语）The coat （that）I put on the desk is blue.（that作宾语）；用于指物，在句中作主语或宾语。
例如：The building which stands near the train station is a supermarket.（作主语）The film （which）we saw last night was wonderful. （作宾语），whom用于指人，who 用作主语，whom用作宾语。
在口语中，有时可用who代替whom。
例如：The girl who often helps me with my English is from England.（作主语）Who is the teacher （whom）Li Ming is talking to（作宾语）注意：1）当关系代词在定语从句中充当宾语时，who、that、which可省略，但介词在关系代词前时，只能用“介词+which/whom”结构（此时关系代词不能用that代替）。
例如：This is the house (which/that) we lived in last year.(可省)This is the house in which we lived last year.(不可省，关系代词不可用that)-Please tell me (whom/that) you borrowed the English novel from.(可省)Please tell me from whom you borrowed the English novel.(不可省，关系代词不可用that)2）关系词只能用that的情况：a. 先行词被序数词或形容词最高级所修饰，或本身是序数词、基数词、形容词最高级时，只能用that，而不用which.例如：He was the first person that passed the exam.This is the most beautiful place that I have been to .b.被修饰的先行词为all，any，much，many，everything，anything，none，the one 等不定代词时，只能用that，而不用which.例如：Is there anything that you want to buy in the shop=I didn't understand the words all that he said.c.先行词被the only，the very，the same，the last，little，few ，no，just等词修饰时，只能用that，而不用which.例如：】This is the same bike that I lost.这就是我丢的那辆自行车。
d. 先行词里同时含有人或物时，只能用that，而不用which.例如：I can remember well the persons and some pictures that I saw in the room.e.以who或which引导的特殊疑问句，为避免重复，只能用that.例如：Who is the girl that is crying 正在哭泣的那个女孩是谁f.主句是there be 结构，修饰主语的定语从句用that，而不用which.例如：There is a book on the desk that belongs to Tom. 桌子上那本书是汤姆的。
3）关系词只能用which，而不用that 的情况：a.先行词为that，those时，用which，而不用that.例如：What’s that which is under the desk 在桌子底下的那些东西是什么，b.关系代词前有介词时，一般用which，而不用that.例如：（同（1））This is the room in which he lives. 这是他居住的房间。
c.引导非限制性定语从句，用which，而不用that.例如：Tom came back，which made us happy. 汤姆回来了，这使我们很高兴。
五、关系副词的用法（1）when指时间，其先行词表示时间，在句中作时间状语。
例如：This was the time when he arrived.这是他到达的时间。
（2）where指地点，其先行词表示地点，在句中作地点状语。
例如：This is place where he works.这是他工作的地点。
（3）why 指原因，其先行词是原因，起原因状语作用。
例如：[Nobody knows the reason why he is often late for school. 没人知道他为什么上学总迟到。
注意：“介词+which/whom”结构有时可与其他关系代词或关系副词互相转换That is the house where my father used to live.=That is the house which my mother used to live in.= That is the house in which my mother used to live.上句中：in which = where六：练习(一)1． Did you find the notebook ______ Jim had given me for my birthdayA. whoB. whomC. whichD. whose-2. That's all ______ I have seen and heard.A. whichB. thatC. whereD. what3. Have you seen the man ______ plan we were talking about ______ yesterdayA. who, themB. its, themC. whose,/D. whose, themOscar is one of the film prizes ______ offered to any Chinese actor or actress so far.A. which are notB. that have not beenC. that has notD. that has not been5. He never reads anything ______ is not worth reading.A. thatB. asC. whoD. which6. The man ________ coat is black is waiting at the gate.A. who'sB. whoseC. thatD. of which~7. _________ cleans the classroom can go home first.A. AnyoneB. those whoC. HoweverD. The one who8. The police caught the man _______ stole my handbag.A. heB. thatC. whomD. which9. The girl ________ is reading under the tree ________ my sister.A. which, isB. whom, wasC. who , isD. who, was10. George Mallory was an English teacher _______ loved climbing.A. whoB. whomC. heD. which11. Don’t talk about such things of _______ you are not sure.A. whichB. whatC. asD. Those12. Is this the factory __________ you visited the other dayA. thatB. whereC. in whichD. the one~13. Is this factory __________ some foreign friends visited last FridayA. thatB. whereC. whichD. the one14. Is this the factory __________ he worked ten years agoA. thatB. whereC. whichD. the one15. The wolves hid themselves in the places __________ couldn’t be found.A. thatB. whereC. in whichD. in that16. Can you lend me the novel ______ the other dayA. that you talkedB. you talked about itC. which you talked withD. you talked about17. Is there anything _______ to youA. that is belongedB. that belongsC. that belongD. which belongs18. ---- “How do you like the book”---- “It’s quite different from _______ I read last month.”A. thatB. whichC. the oneD. the one what19. They were interested _______ you told them.A. in whichB. in thatC. all thatD. in everything20. ---- Do you know the town at all--- No, this is the first time I ________ here.A. wasB. have beenC. cameD. am coming初中英语定语从句练习题（二）1. I still remember the night _______I first came to the house.2. I'll never forget the day________ we met each other last week.3. Mr Black is going to Beijing in October, _______is the best season there.4. I will never forget the days _______I spent with your family.5. I'll never forget the last day______ we spent together.6. This is the school ______I used to study.7. Do you still remember the place______ we visited last week？8. Do you still remember the place_______ we visited the painting exhibition？9. Have you ever been to Hangzhou,_____is famous for the West Lake？10. Have you ever bee to Hangzhou, ______lies the West Lake？11. Tom will go to Shanghai,______live his two brothers.12. I live in Beijing,____is the capital of China.13. There was a time ______there were slaves in the USA.14. It is the third time ______you have made the same mistake.15. It was in the street _____I met John yesterday.16. It was about 600 years ago____the first clock with a face and an hour hand was made.17. The moment _____I saw you, I recognized(认出)you.18. This is the very novel about____we've talked so much.19. This is the way____he did it.20. Who is the student _____was late for school today初中英语定语从句练习题（三）（将下列每组句子改写为带有定语从句的复合句。