I. 定义：定语是修饰名词或代词的成分,定语可由单词、短语来充当。当用一个句子来充当名词或代词的修饰语时，这种起定语作用的句子就被称为定语从句。

They have a clever son.

Do you know the man over there?

I know the man who wrote the book.

II. 要点：

1．  定语从句的前面都有先行词（被修饰语）

This is the boy whom we are looking for

2．  定语从句应紧跟在先行词之后

3．  先行词与定语从句之间要有关系词（有时可省略）

4．  关系词在定语从句中充当某一成分

The girl who is standing under the tree is my sister.

The man whom you want to see has come.

III. 关系词基本用法

但that 一般可用来代替who, whom, which,作宾格时可省略

Do you remember the teacher that/who taught us English?

A bookstore is a store that/which sells books.

The man (that/whom/who) you know is a famous professor.

A) that 不能用来替代who, whom, which的两种情况

1）“介词+whom/which”的结构中，不能用that

She is a good student from whom we should learn.

2) 在非限制性定语从句中，逗号后面不能用that

She sang a new song, which we like very much.

注意：非限制性定语从句的关系代词不能省略

B) 用that不用which的一些特殊情况

1)      先行词为all, much, little, something, anything, everything, nothing等

Is there anything (that) I can do for you?

2)      先行词前有形容词最高级修饰

This is the most exciting report that I have ever read.

3)      先行词前有first, last, next, only, very, all, any等词修饰

The first step (that) we are to take is very difficult.

4)      先行词同时含有“人”和“非人”时，用that 不用which，也不用who/whom

He talked about the people and the books that interested him.

C) 关系副词when, where, why

用关系副词when时，它的先行词是表示时间的名词，用where时先行词是表示地点的名词，而用why时它的先行词只可能是reason，使用时应注意以下几点：

1）  关系代词的选择主要是看先行词在从句中所作的成分

This is the city where I was born.

This is the city (which/that) he has visited

I don’t know the reason why she is late.

That is the reason (which/that) everybody knows

Do you still remember the day when he arrived?

Do you still remember the day (that/which) we spent together?

2）  关系副词when,where, why可由“介词+which”的结构来替代

Is this the reason for which they came?

He left the day on which I came.

注意：how 不能用来引导定语从句

This is the way how he did it.

D) As 作关系代词的用法

与the same, such连用

This is the same book as I read last week.

Such books as I have read are classical works.

练习：

1.       The book ______ is yellow was given to me by Mr. Li.

A)     it’s cover                        C) whose cover

B)      its cover                       D) the cover of that

2.       Who was the grey-haired old woman ______ at yesterday’s meeting?

A)     we saw her                    C) we saw

B)      we saw whom                D) she was seen

3.       He makes good use of the time ______ he can spare.

A)     when                        C) that

B)      in that                D) in which

4.       I don’t know the room ______

A)     where our headmaster lives in       

B)      our headmaster lives in

C)     in that our headmaster lives

D)     in which does our headmaster live

5.       This is the least interesting book ______

A)     which I have ever read  C) what I have ever read

B)      I have ever read         D) which I have ever read

6.       You must do everything _____ I have told you to.

A)     which         B) that   C) when        D) how

7.       Has all _____ can be done _____?

A)     what/done           C) that/been done

B)      that/be done        D) what/ already done

8.       Oct. 1, 1949 is the day _____ even a small child can well remember.

A)     when        B) that   C) what         D) why

9.       That was the room ______ they pretended to be working hard.

A)     which        B) in that        C) in which       D) that

10.   This is the reason ______ I love to read the story.

A)     Why         B) because       C) when       D) since

11.   She had three sons, all ______ became doctors.

A)     of which        B)  which        C) of whom       D) who

12.   Have you bought the same dictionary ______ I referred to yesterday?

A)     that           B) which        C) what        D) as

13.   The doctor ______ stepped in.

A)     Della was waiting for him

B)      whom Della was waiting

C)     Della was waiting for

D)     who Della was waiting

14.   I want to buy such a dictionary _____ you bought last week.

A)     that           B) what         C) like          D) as

15.   This is the TV station ______ we visited last year.

A)     Where        B) that           C) to which       D) in which

16.   Do you still remember the days ______ we spent together in Australia?

A)     when        B) during which        C) which       D) on which

17.   Have you ever asked him the reason _____ may explain his absence?

A)     why  B) when                C) that        D) what

18.   Mary is good at English and mathematics, ______ we all know very well in our school.

A)     that           B) what         C) /               D) as

19.   Let’s go and visit Mr. Brown, ______ you know visited us last year.

A)     that           B) who          C) whom        D) whose

20.   She is pleased with ______ you have given her and ______ you have told her.

A)     that/that       B) what/that      C) what/all what D) all/what

21.   I, who ____ your friend, will try my best to help you.

A)     be             B) am           C) are           D) is

22.   I’ll remember the days and nights ______ we were together in Australia.

A)     when        B) that           C) at which       D) at when

23.   The world ______ is made up of matter.

A)     in that we live                C) on which we live

B)      where we live in            D) we live in

24.   This is the most difficult book ______.

A)     what I have ever read  C) which I have ever read

B)      I have ever read it        D) that I have ever read

25.   There comes a time in every man’s life ______.

A)     then he has to think         C) when he has to think

B)      therefore he has to think D) about which he has to think

26.   He spoke confidently, _____ impressed me most. 

A) so that         B) that               C) it                     D) which

27.   He took down a square green bottle, _____ he poured into a dish. 

A) its content     B) which content     C) the content of which      D) the content of that

28.   It wasn’t such a good dinner _____ she had promised us.

A) that                   B) which                          C) as                            D) what

29.   All _____ is a continuous supply of the basic necessities of life.

A) what is needed     B) for our needs       C) the thing needed     D) that is needed

30.   The goals _____ he had fought all his life no longer seemed important to him.

A) after which      B) for which              C) with which              D) at which

31.   The time is not far away _____ modern communications will become widespread in China’s vast countryside. 

A) when           B) as               C) until                  D) before

32.   The residents, _____ had been damaged by the flood, were given help by the Red Cross. 

A) all whose homes                             B) all their homes

C) all of whose homes                     D) all of their homes

33.   Language is a city, to the building of _____ every human being brought a stone. 

A) which          B) that               C) it                      D) this

34.   You will want two trees about ten feet apart, from _____ to suspend your tent.

A) there            B) them                C) where                    D) which

35.   The mere fact _____ most people believe nuclear war would be madness does not mean that it will not occur. 

A) what            B) which                     C) that                  D) why

36.   The course normally attracts 20 students per year, _____ up to half will be from overseas. 

A) of whom        B) for whom              C) with which              D) in which

37.   I’ve never been to Beijing, but it’s the place _____. 

A) where I’d like to visit                       B) I most want to visit

C) in which I’d like to visit                 D) that I want to visit it most

38.   We grow all our own fruit and vegetables, _____ saves money, of course. 

A) which          B) as               C) that                  D) what

39.   Today the public is much concerned about the way _____. 

A) nature is being ruined                       B) which nature is ruined

C) on which to ruin nature                      D) of nature to be ruined