1．定语从句的功用和结构
在复合句中，修饰某一名词或代词的从句叫做定语从句。被定从句修饰的词叫做先行词。定语从句必须放在先行词之后。引导定语从句的关联词有关系代词和关系副词。例如：
This is the present that he gave me for my birthday
2．关系代词和关系副词的功用
关系代词和关系副词用来引导定于从句，在先行词和定语从句之间起纽带作用，使二者联系起来。关系代词和关系副词又在定语从句中充当一个成分。关系待客做主语，宾语，定语，关系副词可作状语。
（1）作主语：关系代词在定语从句中作主语时，从句的谓语动词的人称和数须和先行词一致。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） 作宾语：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） 作定语
关系代词whose在定语从句中作定语用。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 ）作状语
I’ll never forget the day when I first came to Beijing.
3. 各个关系代词和关系副词的具体用法
（1） who 指人，在定语从句中作主语。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，在定语从句中作宾语。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，在定语从句中作定语。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，在定语从中作主语或宾语。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，有时也指人，在定语从句中作主语或宾语。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 指时间，在定语从句中作状语。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 指地点，在定语从句中作状语。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. 关系代词 whom， which 在定语从句中作介词宾语时，可以和介词一起放于先行词与定语从句之间，有时为了关系紧凑也可以将 whom 与 which 与先行词紧挨着书写，而将介词置于定语从句的后面，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. 具体使用时还要注意下列问题：
(1) 只能使用that,不用which 的情况：
a.先行词是all, few, little, nothing, everything, anything 等不定代词时。例如：
All that he said is true.
b. 先行词被only, no, any, all,等词修饰时。例如：
He is the only foreigner that has been to that place.
c.先行词是序数词或被序数词修饰的词。例如：
He was the second (person) that told me the secret.
d.先行词是形容词最高级或被形容词最高级修饰的词。
This is the best book (that) I have read this year.
e. 先行词既包括人又包括物时。例如：
He talked about the people and the things he remembered.
(2)只能用which，不用that 的情况：
a.在非限制性定语从中。例如：
The meeting was put off, which was exactly what we wanted.
b. 定语从句由介词+关系代词引导，先行词是物时。例如：
The thing about which he is talking is of great importance.
考查的主要形式是单项填空、完型填空、短文填空和完成句子。阅读理解和书面表达肯定也要用到定语从句。
