定义：在复合句中，修饰主句中的某一名词或代词的句子(从句)叫定语从句。

　　A doctor is a person who looks after the sick people’s health.

　　先行词 关系代词 谓语 宾语

　　(定语从句修饰先行词)

　　其中，who是关系代词，在定语从句中做主语。

　　先行词：被定语从句修饰的词叫先行词，通常位于定语从句之前。

　　关系词：引导定语从句的词叫关系词。它既起连接作用，又充当从句中的一个成分。

　　含定语从句的复合句的基本结构为：先行词+关系词+定语从句

　　This is the school where my mother works.

　　先行词=关系词

　　如：That is the bike which my father bought for me. which= bike

　　考点：引导词的选择

　　定语从句的引导词：

　　关系代词 that、which、who、whom(宾格)、whose;

　　关系副词 when、where、why

　　关系代词

　　1. Do you know the girl who/that has got an “A” in the exam?

　　2. She has got a computer which/that her parents bought for her.

　　3. This is the factory that/which his father visited three years ago.

　　4. The boy whose father is a doctor studies very hard.

　　5. The room whose window is open is mine.

　　6. I still remember the day when you left for Beijing.

　　7. This is the factory where I worked three years ago.

　　8. Could you explain the reason why you were late again?

　　注意：

　　一、which与that指物时可互相代替，但也有只能用that不能用which引导的定语从句：

　　口诀：两代限形特疑序

　　①两：先行词词中同时含有“人”和“物”的名词时，定语从句只能用that引导。

　　I can remember the persons and the pictures that I saw in the room.

　　②代：先行词为everything、something、anything、nothing、all、none、much、little、few等不定代词或被这些不定代词修饰时，定语从句只能用that引导。

　　Here is all the money (that) I have.

　　③限：先行词同时又被the only、the very或the right修饰时，定语从句只能用that引导。

　　It is the only word that I know in the passage.

　　④形：先行词同时又被形容词最高级修饰时，定语从句只能用that引导。

　　This is the most interesting story that I have ever heard.

　　⑤特疑：当主句是who或 which开头的特殊疑问句时，用that引导定语从句。

　　Who is the girl that won the first place?

　　⑥序：先行词同时又被序数词修饰时，定语从句只能用that引导。

　　This is the first composition that he has written in English.

　　二、不能使用that的定语从句

　　1、主句与从句用逗号隔开，先行词是物时，只用which，不用that。

　　She heard a terrible noise, which brought her heart into her mouth.

　　2、关系代词前有介词时。(关系词前有介词时，关系词只能为which或whom)

　　This is the hotel in which you will stay.

　　Who is the teacher to whom Lily is talking?

　　3、先行词是one(s)、anyone、someone、those时，关系词使用who。

　　Those who want to go to the Great Wall sign up here.

　　三、关系词的省略

　　关系词在从句中作宾语可省略;但关系代词which, whom在从句中做介词的宾语且介词位于关系代词前时，不可

　　以省略;that、which、who在从句中做主语时，不能省略。

　　1、The boy (who/ that) I like isn’t here now.(作宾语，可省略)

　　2、I’ll never forget the day on which I joined the army.

　　3、Who is the boy that is talking with our teacher?

　　注：判断关系词的成分可以通过还原法，即把先行词带入从句 中，先行词的成分就是关系词的成分。

　　四、whose 指人，也可指物，表示某人的或 某物的，在从句中作定语，不可省略。Please show me the book whose cover is red.