干货：必学英语语法之定语从句
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1. 定义及相关术语
（1） 定语从句：
修饰某一名词或代词的从句叫定语从句。定语从句紧跟在它所修饰的先行词之后。
（2） 先行词：被定语从句修饰的词叫先行词。
（3） 关系词：引导定语从句的词叫
（4） 关系词三个作用：引导定语从句；代替先行词；在定语从句中担当一个成分。
The man who is shaking hands with my father is a policeman.
该句中，who is shaking hands with my father 是定语从句，修饰先行词the man， “who”是引导定语从句的关系词，代替先行词the man，在定语从句中作主语。
2. 关系代词引导的定语从句
（1） who 指人，在定语从句中作主语。
The boys whoare playing football are from Class One. 正在踢足球的男孩是一班的。Yesterday I helped an old woman who had lost his way. 昨天我帮助了一位迷路的老人。That is the teacher who teaches us physics. 那就是教我们物理的老师。
（2）whom 指人，在定语从句中做宾语，常可省略。
Mr. Liu is the person ( whom ) you talked about on the bus. 刘先生就是你们在公共汽车上谈论的那个人。Li Ming is just the boy ( whom ) I want to see. 李明正是我想要见的男孩。The professor ( whom ) you are waiting for has come. 你正在等的教授已经来了。The girl ( whom ) the teacher often praises is our monitor. 老师经常表扬的那个女孩是我们的班长。
（3）Which 指物，在定语从句中做主语或宾语，做宾语时常可省略。
Football is a game which is liked by most boys. 足球是大多数男孩所喜欢的运动。He likes to read books which are written by foreign writers. 他喜欢外国作家写的书。The house which is by the lake looks nice. 湖边的那幢房子看上去很漂亮。This is the pen ( which ) he bought yesterday. 这是他昨天买的钢笔。The film ( which ) they went to see last night was not interesting at all. 他们昨晚看的电影一点意思也没有。
（4）that 指人时，相当于who 或whom；指物时，相当于which。在定语从句中作主语或宾语，作宾语时常可省略。
The number of people that / who come to visit this city each year reaches two million. 每年来参观这座城市的人数达2百万。The person that /whom you introduced to me is very kind. 你介绍给我的那个人很友好。The season that / which comes after spring is summer. 春天以后的季节是夏季。Yesterday I received a letter that / which came from Australia. 昨天我收到了一封来自澳大利亚的信。
（5）whose 通常指人，也可指物，在定语从句中做定语。
I visited a scientist whose name is known all over the country. 我拜访了一个全国知名的科学家。He has a friend whose father is a doctor. 他有一个爸爸当医生的朋友。I once lived in the house whose roof has fallen in. 我曾经住在那幢屋顶已经倒塌了的房子里。
注意！指物时，常用下列结构来代替：The classroom whosedoor is broken will soon be repaired.The classroom the door of which is broken will soon be repaired.Do you like the book whose cover is yellow?Do you like the book the cover of which is yellow?
3. “介词+关系代词”引导的定语从句
关系代词在定语从句中作介词宾语时，从句常常由“介词+关系代词”引出。
The school (which / that) he once studied in is very famous.The school in which he once studied is very famous. 他曾经就读过的学校很出名。Tomorrow I’ll bring here the magazine (which / that) you asked for.Tomorrow I’ll bring here the magazine for which you asked.明天我将把你要的杂志带来。
4. 关系副词引导的定语从句
（1）when 指时间，在定语从句中作时间状语。
I still remember the day when I first came to this school. 我仍然记得我第一次来到这所学校的那一天。The time when we got together finally arrived. 我们团聚的时刻终于到了。October 1, 1949 was the day when the People’s Republic of China was founded.1949年10月1日是中华人民共和国成立的日子。
（2）where 指地点，在定语从句中作地点状语。
Guangzhou is the city where I was born. 上海是我出生的城市。The house where I lived six years ago has been pulled down. 我十年前住的房子已经被拆掉了。I visited the farm where a lot of cows were raised. 我参观了那个饲养了许多奶牛的农场。Is this the place where they fought the enemy? 这是他们当初打敌人的地方吗？
（3）why 指原因，在定语从句中作原因状语。
Please tell me the reason why you missed the plane. 请告诉我你误机的原因。The reason why he was punished is unknown to us. 他受惩罚的原因我们都不知道。I don’t know the reason why he looks unhappy today. 我不知道他今天为什么看上去不愉快。
注意：关系副词引导的定语从句经常可以用“介词+关系代词”引导的定语从句来表示。
From the years when / in which he was going to primary school in the country he had known what he wanted to be when he grew up. 自从他在农村读小学时，他就已经知道长大后要做什么。The reason why / for which he refused the invitation is quite clear. 他为什么拒绝接受邀请的原因是十分明了的。
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