定语从句
定语从句是用来修饰、描述或提供有关名词、代词或整个主句信息的从句。它在整个句子中起形容词的作用。被修饰的名词，语法上称作先行词。从句由关系代词或关系副词引导。关系代词和关系副词不仅起引导定语从句、连接先行词的作用，同时还充当定语从句中的一个成分，如：主语、宾语、介词宾语、表语、定语或状语等。定语从句由下列关系代词和关系副词引导：
(1) who, whom, that(2) which, that(3) whose(4) when, Where(5)why
1. 关系代词who， that ,which在从句中修饰、指代人或事物，作主语。 例句: I thank the woman. She helped me.
a. I thank the woman who helped me. b. I thank the woman that helped me. 例句: Did you hear about the earthquake? It happened in San Francisco last week. a. Did you hear about the earthquake that happened in San Francisco last week? b. Did you hear about the earthquake which happened in San Francisco last week? 你听说上星期在旧金山发生的地震了吗？
关系代词that / which引导的定语从句修饰名词earthquake。在从句that / which happened in San Francisco last week 中作句子的主语。“” 注意：当关系代词在从句中作主语时不能省略。a. b. 两例句意思一样. Which 要比that正．．式一些。
2. 关系代词who(whom)， that ,which在从句中修饰、指代人或事物，在从句中作宾语. Whom 是宾格形式， 常用于较正式的英语中。who和that,which 常用于口语和非正式的英语中。在口语和非正式英语中更多的情况下，作动词宾语的关系代词常被省略。 例句:The man told me to come back. I saw him in the office. a. The man whom I saw in the office told me to come back. b. The man who I saw in the office told me to come back. c. The man that I saw in the office told me to come back. d. The man I saw in the office told me to come back. 我在办公室见到的那为男士叫我回去。 例句: The movie wasn’t very good.
We saw it last night. a. The movie that we saw last night wasn’t very good. b. The movie which we saw last night wasn’t very good. c. The movie we saw last night wasn’t very good. 我们昨晚看的那部电影不怎么样。
关系代词that / which 引导的从句修饰名词The movie。在从句that we saw last night中，that/ which 作动词saw的宾语。关系代词作动词宾语的时候可以省略。
注意：a. 引导从句的关系代词一定要放在从句的最前面，例如： 从句whom I saw in the office，虽然关系代词whom 在句子中作动词的宾语，也应放在从句的最前面。 b. 从句应尽可能地紧跟在所修饰的名词后面。从句whom I saw in the office是用来修饰the man, 所以应放在the man 后面。
3. 关系代词作介词宾语
当关系代词在从句中作介词的宾语时，正式英语中，往往将介词提到关系代词前面。 （3） The woman spoke French. I traveled with her.
a. The woman with whom I travelled spoke French. 和我一起旅行的那位女士讲法语。
注意：在这类句子中修饰、指代人物时，只能用whom 。关系代词不可以用who 或that。 也不可以省略
关系代词。
在口语和非正式英语中，介词往往放在原来的位置，即：在谓语动词之后。在这种情况下，关系代
词可以是who/ whom/that， 也可以省略。
b. The woman whom I travelled with spoke English. c. The woman who I travelled with spoke English. d. The woman that I travelled with spoke English. e. The woman I travelled with spoke English. 在从句中，如果关系代词是作介词的宾语，正式英语中需要前置，即，将介词置于关系代词之前。
例句: He is standing on a chair. Is it firm enough?
a. Is the chair on which he is standing firm enough? 他站的那把椅子结实吗？
on which he is standing 是which引导的从句，修饰the chair。Which在从句中作介词on的宾语。在英语口语和非正式的英语中，介词可以放在动词的后面。关系代词可以用which, that, 也可以省略。
b. Is the chair which he is standing on firm enough? c. Is the chair that he is standing on firm enough? d. Is the chair he is standing on firm enough?
在例句b. c. d. ，从句that he is standing on中的介词后置，关系代词作介词on的宾语，可以用that/which, 也可以省略。 4. 表示所有格关系
whose 用来表示所属关系，它的意思相当于：his, her, its, their等等。Whose 可以用来修饰人，也可以修饰物。whose和它所修饰的名词都置于句首。 (1) 修饰人物
（1） The man called the police.
His wallet was stolen. ａ． The man whose wallet was stolen called the police. 钱包被窃的那个男人给警察打了电话。
Whose引导的从句whose wallet was stolen，修饰the man. Whose 在从句中起定语作用，修饰wallet， 意思是his。 (2) 修饰事物
(2) I’m working in the house.
Its walls are made of glass. ( The walls of the house are made of glass.) a. I’m working in the house whose walls are made of glass. 我在那座四面墙都是玻璃的房子里工作。
whose walls = the walls of the house whose = of which 5. 修饰表示时间的名词
When 引导的从句往往是用来修饰一个表示时间的名词，如：time, year, month, day,
century 等等。When 在从句中起时间状语的作用。 （1）I’ll never forget the day. I met you then (on that day). a. I’ll never forget the day when I met you. b. I’ll never forget the day on which I met you. 我永远也忘不了见到你的那一天。
例句a. 中when引导的从句修饰the day. When在从句中起时间状语的作用，意思是
on the day. 因此，when可以用on which替代。 （2）1949 is the year. The new China was founded then (in that year). a. 1949 is the year when the new China was founded. b. 1949 is the year in which the new China was founded. When引导的从句修饰表示时间的名词the year. 1949年是新中国成立的那一年。
When在从句中作时间状语，意思是in that year. 在此句中，when 可以用in which 来替换。看例句b. 在句中，which 指代的是the year.
(3) 7:50 is the time.
My plane arrives then (at that time). a. 7:50 is the time when my plane arrives. b. 7:50 is the time at which my plane arrives. 7:50 是我乘坐的飞机到达的时间。
When引导的从句修饰名词the time, when在从句中作时间状语。意思是at that
time.在这句话中，
when可以用at which替代。 6. 修饰表示地点的名词
Where引导的从句用来修饰表示地点的名词，例如：city, country, room, house等等。Where 在从句中起地点状语的作用。 (1) The building is very old.
He lives there (in that building).
a. The building where he lives is very old. b. The building in which he lives is very old. c. The building which he lives in is very old. d. The building that he lives in is very old. e. The building he lives in is very old. 他住的那座楼很旧。
a. Where引导的从句修饰名词building. Where在从句中作地点状语，意思是in that
定语从句讲解方法
