什么叫定语（英语的）?

什么叫定语（英语的）?
大家帮一下我这个无知的孩子吧

定语 是用来修饰、限定、说明名词或代词的品质与特征的.
主要有形容词 此外还有名词、代词、数词、介词短语、动词不定式（短语）、分词、定语从句或相当于形容词的词、短语或句子都可以作定语.
The little boy needs a blue pen.(little修饰名词boy；blue修饰名词pen.）/小男孩需要一支蓝色的钢笔.
Tom is a handsome boy./Tom是个英俊的男孩.
There is a good boy./有个乖男孩.
数词作定语相当于形容词：Two boys need two pens./两个男孩需要两支钢笔.
The two boys are students./这两个男孩是学生.
There are two boys in the room./房间里有两个男孩.
代词或名词所有格作定语：
His boy needs Tom's pen./他的男孩需要Tom的钢笔.
His name is Tom./他的名字是汤姆.
There are two boys of Tom's there./那儿有Tom家的两个男孩.
介词短语作定语：
The boy in the classroom needs a pen of yours./教室里的男孩需要你的一支钢笔.
The boy in blue is Tom./穿蓝色衣服的孩子是汤姆.
There are two boys of 9,and three of 10./有两个9岁的,三个10岁的男孩.
名词作定语： The boy needs a ball pen./男孩需要一支圆珠笔. It is a ball pen
./这是一支圆珠笔.
There is only one ball pen in the pencil box./这铅笔盒里只有一支圆珠笔.
副词作定语：
The boy there needs a pen./那儿的男孩需要一支钢笔.
The best boy here is Tom./这里最棒的男孩是Tom.
不定式作定语：
The boy to write this letter needs a pen./写这封信的男孩需要一支钢笔.
The boy to write this letter is Tom./将要写这封信的男孩是汤姆. There is nothing to do today./今天没有事要做.
分词（短语）作定语：
The smiling boy needs a pen bought by his mother./那个微笑的男孩需要一支他妈妈买的钢笔.
The pen bought by her is made in China./她买的笔是中国产的. There are five boys left./有五个留下的男孩.
定语从句：
The boy who is reading needs the pen which you bought yesterday./那个在阅读的男孩需要你昨天买的钢笔.
The boy you will know is Tom./你将认识的男孩叫汤姆.
There are five boys who will play the game./参加游戏的男孩有五个. 定语的位置一般有两种：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.