定语从句的用法

一个句子跟在一名词或代词（先行词）后进行修饰限定，就叫做定语从句。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.

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.

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 very person whom we must take good care of.

(2)引导非限制性定语从句时，必须用关系代词which，不用that,如：I have lost

my bag, which I like very much.

(3)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.

注意在下面几种情况下必须用that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时。为避免重复，如：Who is the man that is giving us the class?

6.由when,where,why引导的定语从句，如：

I don't know the reason why he was late.

This is the place where we have lived for 5 years.

I'll never forget the day when I met Mr Li for the first time.

注意：先行词是表示地点时，如果从句的谓语动词是及物的，就用 that(which)，如果从句的谓语动词是不及物的，就用where引导。This is the house Which /that he has lived in for 15 years.(Where he has lived for 15 year.)

7. 限制性定语从句和非限制性定语从句

(1)限制性定语从句是句中不可缺少的组成部分，主句和从句之间不用逗号分开。引导非限制性定语从句的关系代词有who, whom, whose, which, of which等，这些关系代词都不能省略。

(2)非限制性定语从句是对主句先行词的补充说明，没有这种从句，不影响主句意思的完整，一般用逗号把主句和从句分开，关系代词用which,不用that；指人时可用who，如：I have two brothers, who are both students.

8．如何简化定语从句

(1)定语从句简化为形容词或形容词短语作后置定语。如：

My grandfather lives in a village that is far away from here.

→My grandfather lives in a village far away from here.我祖父住在离这儿很远的一个村子。

This is a book that is worth reading.

→This is a book worth reading. 这是一本值得看的书。

(2)定语从句简化为现在分词或现在分词短语作前置或后置定语。

The man who is standing under the tree is our English teacher.

→The man standing under the tree is our English teacher.

站在树下面的那个人是我们的英语老师。

I saw the house that was burning at that time.→I saw the burning house at that time.

当时我看到那房子在燃烧。

(3)定语从句简化为过去分词短语作后置定语。

I like to see the films which are directed by Zhang Yimou.→I like to see the films directed by Zhang Yimou. 我喜欢看张艺谋导演的电影。

She is the girl who was praised at the school meeting.→She is the girl praised at the school meeting. 她就是在校会上受表彰的那个女孩。

(4)定语从句简化为不定式作后置定语。

He is always the first person that comes to school.→He is always the first person to come to school.他总是第一个到校。

The report which will be given tomorrow is important to us.→The report to be given tomorrow is important to us. 明天要作的报告对我们很重要。

(5)定语从句简化为what 从句。

I couldn't remember the words that he said.→I couldn't remember what he said.

我记不得他说的话。