定语从句中关系代词的选用主要由先行词决定。关系代词一般有that ， which。以下是小编带来关系代词的相关内容，希望对你有帮助。
【语法】
（1） 关系代词who，whom，whose，that，which，as的用法
英语中的关系代词有who，whom，whose，that，which，as，它们是用来引导定语从句的。关系代词既代表定语从句所修饰的词，又在其所引导的从句中承担一个成分， 如主语、宾语、表语或定语。如：
This is the man who saved your son.
这就是救了你儿子的.那个人。（who在从句中作主语，先行词是man）
The man whom I met yesterday is Jim．
我昨天见到的那个人是吉姆。（whom在从句中作宾语，它的先行词是man）
He wants a room whose window looks out over the sea.
他想要个窗户面临大海的房间。（whose在从句中作定语，它的先行词是room）
I walked to the gate that opened towards the lake.
我走向那扇临湖的大门。（that在从句中作主语，它的先行词是gate）
This is the pen which he bought yesterday.（which在从句中作宾语，它的先行词是pen，可省略）
As is known to everybody, the moon travels round the earth once every month.
众所周知，月球每个月绕地球转一周。（as在从句中作主语，指代主句）
（2）关系代词who，whom，whose的区别
a) who和whom均只用于指人，不用于指事或物，其中who在定语从句中用作主语，whom在定语从句中用作宾语。Who有时可代替whom作宾语，但在介词后面一定要用whom作介词的宾语。如：
She said she huffed the persons who flattered her.
她说她看不起那些拍她马屁的人。
The man who / whom you met just now is called Jim.
你刚遇见的那个人叫吉姆。
She brought with her three friends, none of whom I had ever met before.
她带了3个朋友来，我以前都没见过。
b)关系代词whose既可用于指人，也可用于指事或物，它在定语从句中主要用作定语。如：
This is the woman whose name is known all over the country.
这个是一个名字被整个国家所熟知的女科学家。
练习题
1、关系代词who的用法：who“谁”，用来表示人，在定语从句中作主语。这里的who一般可以用that来替换。
【例1】Jack， there is someone in the office_____ would like to speak with you.
A. who B. which C. whom
【研习】先行词是“someone”表示人，所填的关系代词在定语从句中作主语，所以排除B和C选项。故选择A。这里的who可以用that来替换。
2、关系代词that的用法：that 的具体意思由先行词的意思决定，它可以表示人，也可以表示物。作主语表示人时，that和who一般可以互换；作宾语表示人时，that和 whom一般可以互换；作主语、宾语表示物时，that 和which一般可以互换，而且都可以省略。
【例2】The scientist and his achievements________you told me about are admired by us all .
A. that B. which C. who D. whose
【研习】先行词是“the scientist and his achievements”，表示人和物，在定语从句中作主语或宾语只用that。故选择A。
【例3】The boy _______I talked with just now is my best friend .
A. which B. that C. whose D. where
【研习】先行词是“the boy”，表示人作宾语，答案A是物，答案C和D分别作定语和状语，故选择B。这里的that可以用whom来替换(可以省略)。
【例4】The book _______he bought yesterday is very interesting .
A . 不填B. why C. when D. what
【研习】先行词是“the book”，表示物，关系代词作定语从句的宾语；答案B和C作状语，D不能引导定语从句。故选择A。
书香门第
