定语从句是英语中常见的句型，为了方便考生们更好的掌握，考高分网小编今天就来给大家详细讲解一下什么叫定语从句以及定语从句的常考知识点，一起看看吧。
一、什么叫定语从句
一个句子作定语就叫定语从句。
二、定语从句的结构及种类
1.结构：关系词+主语+谓语+其它。
2.种类：限制性定语从句和非限制性定语从句。
三、关系词的分类及关系词
1.关系代词：who，whom, whose, that ,which, as.
2.关系副词：when，where，why.
四、关系词的功用
1.起连接作用，引导定语从句。
2.在定语从句中作一个成分——主语，宾语，状语，定语，表语。
五、什么是先行词
被定语从句所修饰的词是先行词。
1.介词+which/whom
① 介词的选择根据下面四种情况
a.根据定语从句中的谓语动词
Who is the person with whom you shook hands just now?
b.根据定语从句中的形容词
In learning English, he had two things about which he was not sure.
c.根据定语从句所修饰的先行词
This is the bike by which I go to school.
d.根据句意
This is the train on which he works.
② 如果关系词指人，选whom，如果关系词指物，选which。
2.不定代词+of+which/whom
常用的不定代词有：both, neither, either(两者之一)，all, none, many, most, some, any。
Mr. Li has two sons, both of whom are college students.
There are 10.000 books in this library, most of which are interesting.
3.数词，分词，百分数+of+which/whom
There are 50 students in our class, two thirds of whom are girls.
4.the+名词+of+which=whose+名词
He has just bought a magazine, the cover of which (=whose cover) is missing.
5.介词+whose+名词
This is our school teaching building, on whose top there is a red flag.
由于篇幅较长，考生可以
1.非限制性定语从句
如果主语和定语从句之间有个逗号，它就是非限制性定语从句。引导非限制性的定语从句的关系词有：which，who, when, where, why, whom, whose。
2.分隔性的定语从句
有时定语从句和先行词之间被其他词隔开，把这种从句叫分隔性的定语从句。
The days are gone when China used foreign oil.
= Gone are the days when China used foreign oil.
3.The way 作先行词
引导定语从句的关系词有三种情况：that, in which 省略。
I don’t like the way ___D___ you do things.
A. that B. in which C. × D. all of the above
4. One of
Nne of+the+复数名词+定语从句，谓语动词用复数，the only one of +the 复数名词+定语从句，谓语动词用单数。
He is one of the teachers in our school who teach well.
He is the only one of the teachers in our school who teaches well.
1. 在定语从句中，谓语动词的单数，复数依据它所修饰的先行词。
I, who am your teacher, will help you with everything.
He who breaks the school rules should be punished.
Those who break the school rules should be punished.
Anyone who breaks the school rules should be punished.
2. 定语从句和并列句的区别
非限制性的定语从句和主语之间有一个逗号，并列句的结构式单句+并列连词(and, or. so, but)+简单句.
I have many friends, all of whom are kind to me.
I have many friends and all of them are kind to me.
