一、定义：在复合句中，修饰某一名词或代词的从句叫做定语从句。定语 定语用来限定、修饰名词或代词的，是对名词或代词起修饰、限定作用的词、短语（动词不定式短语、动名词短语和分词短语）或句子，汉语中常用‘……的’表示。主要由形容词担任，此外，名词 ，代词 ，数词 ，分词 ，副词 ，不定式以及介词短语 也可以来担任，也可以由一个句子来担任。单词作定语时通常放在它所修饰的词之前，作前置定语。短语和从句作定语时则放在所修饰的词之后，作后置定语。 定语从句是指在一个句子中作定语的句子，定语从句要放在所修饰的词后。如：1) The man who lives next to us is a policeman. 2) You must do everything that I do. 上面两句中的 man 和 everything 是定语从句所修饰的词，叫先行词，定语从句放在先行词的后面。引导定语从句的词有关系代词 that, which, who(宾格 who, 所有格 whose)和关系副词 where, when、why关系词常有三个作用：1、引导定语从句 2、代替先行词 3、在定语从句中担当一个成分二、关系代词引导的定语从句1.who 指人，在从句中做主语(1)The boys who are playing football are from Class One.1(2)Yesterday I helped an old man who lost his way.2. whom 指人，在定语从句中充当宾语，常可省略。 (1) Mr. Liu is the person (whom) you talked about. 注意：关系代词 whom 在口语和非正式语体中常用 who 代替，可省略。 (3) The man who/whom you met just now is my friend.3. which 指物，在定语从句中做主语或者宾语，做宾语时可省略 (1) Football is a game which is liked by most boys. ( which 在句子中做主语) (2) This is the pen (which) he bought yesterday. ( which 在句子中做宾语)4. that 指人时，相当于 who 或者 whom；指物时，相当于 which。在宾语从句中做主语或者宾语，做宾语时可省略。 (5) The people that/who come to visit the city are all here. (在句子中做主语) (6) Where is the man that/whom I saw this morning? (在句子中做宾语)5. whose 通常指人，也可指物，在定语从句中做定语 (1) He has a friend whose father is a doctor. (2) I lived in a house whose roof has fallen in.2 whose 指...
