定语从句

本节导读

定语从句是专升本语法里最重要的从句之一，在词汇与语法题、完形填空、阅读理解和写作里都会遇到。最常见的考法是在空格里选关系词：who、which、that、whose，还是 when、where、why。

学完这一节，你应该能找出先行词，判断从句缺什么成分，从而选对关系词；还要知道 that 什么时候可以用、什么时候不能用，以及非限制性定语从句的特点。

什么是定语从句

修饰名词或代词的从句叫定语从句，被修饰的词叫先行词，引导从句的词叫关系词。关系词有两个作用：把从句和先行词连起来，并在从句里充当一个成分。

英语	说明
The man who is talking to the teacher is my uncle.	先行词是 the man，who 在从句里作主语
This is the house where I used to live.	先行词是 the house，where 在从句里作地点状语

关系代词

关系代词	指代	在从句中的成分	例句
who	人	主语、宾语	The girl who sits next to me is Lucy.
whom	人	宾语（介词后必须用 whom）	The man whom I met is a doctor.
whose	人或物	定语，意思是「……的」	The boy whose father is a doctor is my friend.
which	物	主语、宾语	The book which is on the desk is mine.
that	人或物	主语、宾语	The book that I bought is interesting.

注意 whose 后面直接接名词，不能再加 his、her 等：The boy whose father is a doctor，不能写成 whose his father。

关系副词

关系副词	先行词	相当于	例句
when	表示时间的名词	介词 + which	I will never forget the day when I joined the army.
where	表示地点的名词	in/at which	This is the house where I used to live.
why	the reason	for which	The reason why he was late is not clear.

判断用关系代词还是关系副词，看从句缺什么：从句缺主语或宾语，用关系代词；主语、宾语都齐全，只缺时间、地点、原因状语，用关系副词。

英语	说明
This is the house which I bought last year.	bought 后面缺宾语，用关系代词 which
This is the house where I used to live.	live 后面不缺宾语，缺地点状语，用 where

that 的用法

情况	例句
只能用 that：先行词是 all、everything、nothing、much、little 等不定代词	All that I want to say is thank you.
只能用 that：先行词被 the only、the very、the same、序数词、最高级修饰	This is the best film that I have ever seen.
只能用 that：先行词既有人又有物	He talked about the people and the things that he had seen.
不能用 that：介词后面	This is the house in which he lives.
不能用 that：非限制性定语从句	My brother, who works in Shanghai, is a nurse.