一、基本概念： 在复合句中，修饰某一名词或代词的从句叫定语从句。如： Do you know the man who spoke at the meeting just now? That is the house where he lived ten years ago. 定语从句所修饰的词叫先行词；定语从句一般用关系代词或关系副词来引导，关系词放在先行词与定语从句之间起连接作用，同时又作从句中的一个成分。 引导定语从句的关系代词有：that, who, whom, whose, which; 关系副词有：when, where, why. 二、关系词的用法： （一）关系代词的用法： 1． 作主语用who, which 和that, 如： He is the man who/that lives next door. The train which/that has just left is for Shenzhen. 2． 作宾语用whom, who, which, that, 如： The man (whom/who/that) we have just seen is a famous writer. Where is the book (which/that) I bought last week? 注：在非正式文体中，用于指人的关系代词who whom, that 通常可以省略，但在正式文体中通常用whom, 不可省略；用于指物的关系代词which和that 在非正式文体中也通常省略，但在正式文体中一般不省略。 3． 作定语用whose, 如： (a) He is the man whose car was stolen last week. (b) It was a meeting whose importance I did not realize at that time. 注：“whose +名词中心词”这一结构在定语从句中既能作主语（如上a 句），又能作宾语（如上b 句）。whose 的先行词常用来指人，但有时也可以用来指具体事物或抽象概念，这时可以与of which 结构互换，词序是：“名词+of which”，如： They came to a house whose back wall had broken down.. (= the back wall of which) He’s written a book the name of which I’ve completely forgotten. (= whose name) 4． 作表语只用that ，它既可以指人，也可以指物，但时常省略。如： He is no longer the man that he used to be. This is no longer the dirty place (that) it used to be. （二）关系副词的用法： 1．when 指时间，在从句中作时间状语，它的先行词通常有：time, day, morning, night, week, year 等。如： I still remember the time when I first became a college student. Do you k...
