一. 定語從句的功用和結構
在複合句中，修飾某一名詞或代詞的從句叫做定語從句。被定從句修飾的詞叫做先行詞。定語從句必須放在先行詞之後。引導定語從句的關聯詞有關係代詞和關係副詞。例如：
This is the present that he gave me for my birthday.
Do you know everybody who came to the party?
I still remember the night when I first came to thevillage?
This is the place where Chairman Mao once lived.
二. 關係代詞和關係副詞的功用
關係代詞和關係副詞用來引導定於從句，在先行詞和定語從句之間起紐帶作用，使二者聯絡起來。關係代詞和關係副詞又在定語從句中充當一個成分。關係待客做主語，賓語，定語，關係副詞可作狀語。
1. 作主語：關係代詞在定語從句中作主語時，從句的謂語動詞的人稱和數須和先行詞一致。例如：
I don’t like peoplewho talk much but do little.
The cars which areproduced in Hubei Province sell very well.
2. 作賓語：
She is the personthat I met at the school gate yesterday.
The book that mygrandmother gave me is called “The Great Escape”.
3. 作定語
關係代詞whose在定語從句中作定語用。例如：
What’s the name ofthe young man whose sister is a doctor?
The girl whosefather is a teacher studies very hard.
4. 作狀語
I’ll never forgetthe day when I first came to Beijing.
This is the housewhere I was born.
三. 各個關係代詞和關係副詞的具體用法
1. who 指人，在定語從句中作主語。例如：
The person whobroke the window must pay for it.
The boy who iswearing the black jacket is very clever.
2. whom指人，在定語從句中作賓語。例如：
Do you know theyoung man (whom) we met at the gate？
Mr. Lee (whom) youwant to see has come.
3. whose 指人，在定語從句中作定語。例如：
The girl whosemother is ill is staying at home today.
I know the boywhose father is a professor.
4. which指物，在定語從中作主語或賓語。例如：
A dictionary is abook which gives the meaning of words.
Here is the book(which) the teacher mentioned yesterday.
5. that多指物，有時也指人，在定語從句中作主語或賓語。例如：
I’ve read thenewspaper that(which) carries the important news.
Who is the person thatis reading the newspaper over there?
6. when 指時間，在定語從句中作狀語。例如：
I’ll never forget the time whenwe worked on the farm.
He arrived in Beijing on the day when I left.
7. where 指地點，在定語從句中作狀語。例如：
This is the house where we livedlast year.
The factory where his fatherworks is in the east of the city.
四. 關係代詞 whom， which 在定語從句中作介詞賓語時，可以和介詞一起放於先行詞與定語從句之間，有時為了關係緊湊也可以將 whom 與 which 與先行詞緊挨著書寫，而將介詞置於定語從句的後面，如：
That was the roomin which we had lived for ten years. = That was the room
which we had lived in for ten years.
五. 具體使用時還要注意下列問題：
1. 只能使用that,不用which 的情況：
(1) 先行詞是all, few, little,nothing, everything, anything 等不定代詞時。例如：
All that hesaid is true.
(2) 先行詞被only, no, any, all,等詞修飾時。例如：
He is the onlyforeigner that has been to that place.
(3) 先行詞是序數詞或被序數詞修飾的詞。例如：
He was the second(person) that told me the secret.
(4) 先行詞是形容詞最高階或被形容詞最高階修飾的詞。
This is the bestbook (that) I have read this year.
(5) 先行詞既包括人又包括物時。例如：
He talked about thepeople and the things he remembered.
2. 只能用which，不用that 的情況：
(1) 在非限制性定語從中。例如：
The meeting was putoff, which was exactly what we wanted.
(2) 定語從句由介詞+關係代詞引導，先行詞是物時。例如：
The thing aboutwhich he is talking is of great importance.
舉例1.
---Does the teacher know everybody _______ plantedthe trees?
---Yes, he does.
A. which B. whose C. where D. who
【解析】答案：D。該題考查的是引導定語從句的關係代詞的選擇。因為先行詞是人，而關係代詞又在定語從句中作主語，所以只有who合適。
2.
The letter _______ I received from him yesterdayis very important.
A. who B. where C. what D. that
【解析】答案：D。該題考查的是定語從句的關係代詞的.選擇。因為先行詞是物，而關係代詞在定語從句中作賓語，所以只有that合適。
3.
---Where is the scientist________ gave us the talkyesterday?
---He has gone back to Qinghua University.
A. whom B. who C. whose D. which
【解析】答案：B。該題考查的是引導定語從句的關係代詞的選擇。因為先行詞是人，而關係代詞又在定語從句中作主語，所以只有who合適。
4.
I hate people _______talk much but dolittle.
e B. whom C. which D. who
【解析】答案：D。該題考查的是引導定語從句的關係代詞的選擇。因為先行詞是人，而關係代詞又在定語從句中作主語，所以只有who合適。
