1、关系代词（that, who, whom, whose, which）所代替的先行词是人或物的名词或代词，并在句中充当主语、宾语、定语等成分。
例1. Is he the man who/that wants to see you?（who / that在从句中作主语，指人）
例2. He is the man whom/ that I saw yesterday.（whom / that在从句中作宾语，指人）
例3. They rushed over to help the man whose car had broken down.（whose在句中作定语，指人）
例4. Please pass me the book whose cover is green.（whose在句中作定语，指物。）
2、关系副词（when, where, why,）可代替的先行词是时间、地点或原因的名词，在从句中作状语。关系副词when, where, why的含义相当于"介词+ which"结构，因此常常和"介词+ which"结构交替使用。
例5. Beijing is the place where (in which) I was born.例6. Is this the reason why (for which) he refused our offer?
例7. His father died the year (when / in which) he was born.
例8.He can’t find the place (where / in which) he lived forty years ago.
用关系代词，还是关系副词完全取决于从句中的谓语动词。缺少宾语，就必须要求用关系代词；不缺成分（作状语）用关系副词。
（判断对错）
1. This is the mountain village where I visited last year.
2. I will never forget the days when I spent in the countryside.
例9. This is the museum ____ the exhibition was held.
A. where
B. that
C. on which
D. the one 当堂练习：
1. I still remember the day____we studied together.
I still remember the day____we spent together.
I still remember the day____was his birthday
2.This is the factory___he used to work.
This is the factory___we visited yesterday.
This is the factory___makes this kind of car.
This is the factory___ this kind of car is made.
3.This is the reason___he explained.
This is the reason___he failed in the exam.
This is the reason___can explain why he was late.
