定语从句
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，引导定语从句的有关系代词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。
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.
Do you know the boy who is playing football?
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.
The girl they are talking about is Mary.
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 work shop.
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 person whom we must take good care of.
(2)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，如：
The book that I bought yesterday was written by Lu Xun.
6.由when,where,why引导的定语从句
why=for which
where=in/ at/ on+ which
when=during/ on/ in+which
1. where是关系副词，引导表示地点的定语从句。
This is the place where the accident happened.
2. when引导定语从句表示时间
I still remember the first time when I first met her.
3.why是关系副词，用来引导表示原因的定语从句
I don’t know the reason why he is often late.
注意在下面几种情况下必须用that而不用which引导定语从句。
(1)先行词是不定代词all, few, little, much, something, nothing, anything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.
(3)先行词被all, any, every, each, few, little, no, some等修饰，如
I've 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
He is the only person that I want to talk with.
(5)先行词既有人又有物时，如:
They talked about persons and things that they met.
(6)当句中已有who和which时为避免重复，如：
Who is the man that is smoking?
Which is the book that is written by the famous writer?
巩固练习
一、选择适当的关系代词或关系副词
1 .The second book _______I want to read is Who Moved My Cheese.
A. which B. what C. that D. as
2 .The book______ you need is sold out at the moment.
A. one B. what C. which D. it
3 .Is this the place ______Lincoln once lived. A. that B.in which C. which D. when
4.The clever boy made a hole in the wall________ he could read books at night.
A. in which B. through which C. at which D. on which
5.I'm one of the boys_____ never late for school. A. that is B. who are C. whom is D. who is
6 .The boy______ you met at my home is Tom’s brother.
A. whom B. one C. which D. whose
7 .These books are for students _____ mother language is not English.
A. whom B. that C. which D. whose
8.This is the museum _______they visited last month? A. what B. where C. which D. it
9.The man __________ coat is black is waiting at the gate.
A. who's B. whose C. that D. which
10.The room _________ we do the reading is a reading--room.
A. on which B. in that C. that D. where
11.The village________ we spent our holiday last week is in the south of the province.
A. where B. that C. which D. what
12.I won't tell you the reason _______ I'm so excited. A. because B. why C. how D. which
13.Is this the shop ________sells children's clothing?
A. which B. where C. in which D. what
14.The only language _________ is easy for me to learn is Chinese.
A. which B. whose C. that D. it
15.September 1st, 1997 is the day ________ we'll never forget.
A. that B. when C. on which D. on that
