定语从句中的关系词的选择,通过两个步骤来定，一起来看看定语从句的关系词用法。
一、定语从句的.概念
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），as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。关系词起3个作用：1，引导定语从句。2，代替先行词。3，在定语从句中担当一个成分。
本单元学习关系代词引导的定语从句。
1. who指人，在从句中做主语
The boys who are playing football are from Class One.
Yesterday I helped an old man who lost his way.
2. whom指人，在定语从句中充当宾语，常可省略
Mr. Liu is the person (whom) you talked about on the bus.
Mr. Ling is just the boy whom I want to see.
注意：关系代词whom在口语和非正式语体中有的时候常用who代替，并且可以省略。如：
The man who/whom you met just now is my friend.
3. whose通常指人，也可指物，在定语从句中做定语
He has a friend whose father is a doctor.
I once lived in a house whose roof has fallen in.
whose指物时，常用以下结构来代替：
The classroom whose door is broken will soon be repaired.→ The classroom the door of which is broken will soon be repaired.
Do you like the book whose cover is yellow?→ Do you like the book the color of which is yellow?
4. which指物，在定语从句中做主语或者宾语，做宾语时可省略
Football is a game which is liked by most boys.
This is the pen (which) he bought yesterday.
5. that指人时，相当于who或者whom；指物时，相当于which。在定语从
句中做主语或者宾语，做宾语时可省略
The number of the people that/who visit the city each year rises one million.
Where is the man that/whom I saw this morning?
The number of people who/that lost homes reached 250,000．
It sounded like a train which/that was going under the house．
The boy（whom/that/who）we saw yesterday was John’s brother．
The car（which/that）my uncle just bought was destroyed in the earthquake．
关系代词代替先行词在定语从句中充当主语、宾语、定语，因此定语从句不能再出现关系代词所替代的名词或代词。如：
（误）The story（that/which）you told me it yesterday is interesting．
（正）The story（that/which）you told me yesterday is interesting．
昨天你给我讲的那个故事很有趣。
That 和which在定语从句中指物时，常常可以互换。但下面几种特殊情况，不能互换，只能用that, 不用which.
1）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.
他是第一个通过考试的人。
2）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？
你在商店里有什么东西要买吗？
3）先行词被the only， the very， the same， the last， little， few 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。
4）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.
我能清楚记得我在那个房间所见到的人和一些照片。
5）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？
6）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。
I. 用适当的关系代词that，which，who，whom填空
first thing ______you must do is to have a meal.
l 1st is the day _____is called April Fool’s Day in the west.
family _____had lost everything in a big fire got much help from their friends.
house _____we live in is very old.
’t you see the man ______I talked with just now？
II. 单项填空
1. --- Do you know the man ______is talking with your father？
--- Yes， he’s our headmaster.
A. he C. which D. whom
2. Is this the river _____I can swim？
A. which B. in which C. that D. the one
3. This is the best hotel in the city _____I know.
A. where B. which C. thatD. it
4. Can you lend me the dictionary ______the other day？
A. that you bought B. you bought it
C. that you bought it D. which you bought it
5. Anyone ______with what I said may put up you hands.
A. which agrees B. who agree
C. who agrees D. which agree
6. My watch is not the only thing ______ is missing.
A. that B. it C. which D. who
7. The man ______coat is black is waiting at the gate
A. who’s B. whose C. that D. of which.
8. The girl ______ is reading under the tree _____my sister.
A. which；is B. whom；was C. who；is D. who；was
9. I love places ______the people are really friendly.
A. that B. which C. where D. who
10. The world ______ is made up of matter.
A. in that we live B. on which we live
C. where we live in D. we live in
答案
I. 1. that2. which / that3. who / that4. that / which5. who/ whom/ that
II. 1-5BBCAC6-10ABCCD
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