定义：翻译为"...的”的单词或词组
两大作用：修饰和限定。
修饰或者限定的对象：名词或者代词。
分类：根据定语和所修饰词的位置分为两类：前置定语和后置定语。用在所修饰词之前的叫前置定语，用在所修饰词之后的叫后置定语，定语和中心语之间是修饰和被修饰、限制和被限制的关系。
搞明白这些，我们接下来看看什么样的单词或者词组可以做定语？
1、形容词
既然定语由类似形容词的词构成，那么形容词肯定可以做定语啦！举个例子：
A: He is an English man
B: We need an English teacher.
对比句A和B虽然同一个形容词，但在句子中作为定语的作用是不一样的。前者修饰，后者限定，你明白为什么吗？
C： We have something important to do. (限定作用）
形容词一般情况下作为前置定语，但是当修饰不定代词时，需要放在代词后面，作为后置定语
2. 名词
We have an apple tree.
We need an apple tree. (限定作用，前置定语
同样上面两个apple作为定语修饰tree，但是前者起限定作用，后者起修饰作用。你明白为什么吗？
3. 限定词
限定词又分冠词、指示代词、物主代词和不定代词。
You have a book. 冠词a做前置定语
Who want to choose that beautiful room? 指示代词that做前置定语
She is my elder sister.物主代词my做sister的前置定语
whose handbag is it? 不定代词whose做handbag的定语
We have lots of problems to handle. 不定代词 lots of做problems的定语
Mikes house ， the girls coat. 名词所有格做前置定语
4.数词
There is one book and two pens on the desk.
one和two作为前置定语，分别修饰book和pen，并且起修饰作用
5. 介词短语
介词短语一般放在所修饰词的后面，做后置定语
The boy in the classroom needs a pen of yours.
in the classroom为后置定语，修饰名词boy；of yours为后置定语，修饰名词pen
被修饰词+of +名词 ：(一般有从属关系）
a friend of mine (注意名词性物主代词也相当于名词）
one of my friends.
the love of my mother.
the role of the teacher
a girl of 12
a boy of China
the paintings of Monet : 题外话：指某人所画或所著等的全部作品时，用of，指其作品中的一部或多部时，则用by，比如：a painting by Monet ，two paintings by Monet
被修饰词+to/for +名词：
a ticket to/for The Sound of Music: 意为"...的票/券"
6. 动词不定式（短语）
关于这部分可以去看另外一篇关于不定式的文章，第6条。
7. 分词（现在分词和过去分词）
The smiling boy needs a pen bought by his mother.
现在分词smiling为前置定语，修饰名词boy；bought by his mother为定语，修饰名词pen
There are five boys left.
过去分词left为定语，修饰名词boy； five为定语，修饰名词boy；
the old woman driving a red car. 动名词短语做后置定语
8. 定语从句
定语从句是个重点，也是难点，先举几个例子吧！改天再搞个专题总结一下。
Is he the man （who / that） wants to see you？
He is the man （whom / that ）I saw yesterday.
They rushed over to help the man whose car had broken down.
Prosperity which / that had never been seen before appears in the countryside
9. 同位语从句：
The girls were surprised at the fact that ocean ships can sail up the Great lakes.
练习：（to do）
