1．定語從句的功用和結構
在復合句中，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后。引導定語從句的關聯詞有關系代詞和關系副詞。例如：
This is the present that he gave me for my birthday
2．關系代詞和關系副詞的功用
關系代詞和關系副詞用來引導定于從句，在先行詞和定語從句之間起紐帶作用，使二者聯系起來。關系代詞和關系副詞又在定語從句中充當一個成分。關系待客做主語，賓語，定語，關系副詞可作狀語。
（1）作主語：關系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 people who talk much but do little.
The cars which are produced in Hubei Province sell very well.
（2） 作賓語：She is the person that I met at the school gate yesterday.
The book that my grandmother gave me is called “The Great Escape”.
（3） 作定語
關系代詞whose在定語從句中作定語用。例如：
What’s the name of the young man whose sister is a doctor?
The girl whose father is a teacher studies very hard.
（4 ）作狀語
I’ll never forget the day when I first came to Beijing.
3. 各個關系代詞和關系副詞的具體用法
（1） who 指人，在定語從句中作主語。例如：
The person who broke the window must pay for it.
The boy who is wearing the black jacket is very clever.
（2）whom指人，在定語從句中作賓語。例如：
Do you know the young man (whom) we met at the gate？
Mr Lee (whom) you want to see has come.
（3） whose 指人，在定語從句中作定語。例如：
The girl whose mother is ill is staying at home today.
I know the boy whose father is a professor.
（4） which指物，在定語從中作主語或賓語。例如：
A dictionary is a book 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 the newspaper that(which) carries the important news.
Who is the person that is 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 when we 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 lived last year.
The factory where his father works is in the east of the city.
4. 關系代詞 whom， which 在定語從句中作介詞賓語時，可以和介詞一起放于先行詞與定語從句之間，有時為了關系緊湊也可以將 whom 與 which 與先行詞緊挨著書寫，而將介詞置于定語從句的后面，如：
That was the room in which we had lived for ten years. = That was the room
which we had lived in for ten years.
5. 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：
a.先行詞是all, few, little, nothing, everything, anything 等不定代詞時。例如：
All that he said is true.
b. 先行詞被only, no, any, all,等詞修飾時。例如：
He is the only foreigner that has been to that place.
c.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.
d.先行詞是形容詞最高級或被形容詞最高級修飾的詞。
This is the best book (that) I have read this year.
e. 先行詞既包括人又包括物時。例如：
He talked about the people and the things he remembered.
(2)只能用which，不用that 的情況：
a.在非限制性定語從中。例如：
The meeting was put off, which was exactly what we wanted.
b. 定語從句由介詞+關系代詞引導，先行詞是物時。例如：
The thing about which he is talking is of great importance.
考查的主要形式是單項填空、完型填空、短文填空和完成句子。閱讀理解和書面表達肯定也要用到定語從句。
