who，whom，whose和that作为定语从句的引导词，称为关系代词。我们现在来看一下先行词指人时，这四个关系代词的使用问题。下面用句子合并的方法来分析。
一、定语从句用who或that做引导词，在从句中做主语。
请分析下面两个简单句：句①The boy is called Jack.句②He broke the window.
把句②变为句①的定语从句，句①中的the boy做定语从句的先行词。在句②中he指句①中提到的the boy也就是定语从句的先行词，he在句中做主语，因此要用who和that引导定语从句，代替句②中的he，也就是说he就不能出现在定语从句中了。由此得到句③The boy who broke the window is called Jack.
注意：一般情况下定语从句要紧挨先行词。
请把下面每组的两句话合并为一句。
The person must pay for it./He lost the library book.
→The person who lost the library book must pay for it.
The boy is very clever./He is wearing the black jacket.
→The boy who is wearing the black jacket is very clever.
二、定语从句用who，whom或that做引导词，在从句中做宾语。因为是做宾语，所以这些引导词可以省略。
请分析下面两个简单句：句①Do you know the young man?句②We met him at the gate.
把句②变为句①的定语从句，句①中的the young man做定语从句的先行词。在句②中him指句①中提到的the young man也就是定语从句的先行词，him在句中做宾语，因此要用whom，that或who引导定语从句，代替句②中的him，也就是说him就不能出现在定语从句中了。由此得到句③Do you know the young man who/that/whom we met at the gate?(who/that/whom可以省略，句子可以写作：Do you know the young man we met at the gate?)
请把下面每组的两句话合并为一句。
Mr.Lee has come./You want to see him.
→Mr.Lee who/whom/that you want to see has come.
This is the girl.
He worked with her in the office./→This is the girl whom/that/who he worked with in the office.
三、定语从句用whose做引导词，在从句中作定语表示“某些人的…”。
请分析下面两个简单句：句①The girl is staying at home today.句②Her mother is ill.
把句②变为句①的定语从句，句①中的the girl做定语从句的先行词。在句②中her指句①中提到的the girl也就是定语从句的先行词，her在句中做定语，因此要用whose引导定语从句，代替句②中的her，也就是说her就不能出现在定语从句中了。由此得到句③The girl whose mother is ill is staying at home today.
请把下面每组的两句话合并为一句。
The boy is called LiLei./His parents were dead in the flood.
→The boy whose parents were dead is called LiLei
Mr.Wang is the policeman./His house caught fire last Sunday.
→Mr.Wang is the policeman whose house caught fire last Sunday.
巩固练习：
一、用定语从句把下面两句话合并为一句。
1.Let’s ask the man .He is reading the book over there.
2.The girl is Peter’s sister.We saw her yesterday.
3.This is Uncle Li.He mended computers for us.
4.I know the young man.You mean him.
5.I know the boy.His father is a scientist.
二、单项选择
1.Have you seen the man _____ car was stolen just now?
A.its B.it’s C.whose D.which
2.On the bus I saw a student ____ I thought was your brother.
A.who B.whom C.which D.whoever
3.The foreigner ___ visited our school yesterday is from Canada.
A.that B.which C.whom D./
4.Here is the man ____ you are looking for.
A.which B.whom C.what D.where
答案：
一、
1.Let’s ask the man who/that is reading the book over there.
2.The girl that/whom/who we saw yesterday is Peter’s sister.
3.This is UncleLi who/that mended computers for us.
4.I know the young man whom/that/who you mean.
5.I know the boy whose father is a scientist.
二、1-4 C A A B
