who引导定语从句修饰表示人的名词，who本身在定语从句中作定语。关系代词whom在定语从句中作宾语，一般可以省略。下面就和小编一起了解一下吧，供大家参考。

who有什么用法

who主要用在当先行词表人的情况下，一般在从句中充当主语，但有时也可以作宾语，相当于whom。

如：He's the man who bought these books just now.

The man who I served was wearing a hat.

第一句中的who在从句中作bought的主语，而第二句中的who则作served的宾语。

需要注意的是，当介词位于定语从句的句首时，就不能用who，而要用whom。

如：She is the girl about whom the man talked at the meeting an hour ago.

who也可以用来引导非限定性定语从句。

如：The manager, who comes from Japan, told me to help you with your project.

whom的用法整理

（1）whom主要用在当先行词表人的情况下，在从句中充当动词或介词的宾语。

如：The boy whom you met on the street just now is one of cousins.

He is the man from whom you ought to ask for help.

（2）whom也可以用来引导非限定性定语从句。

如：The soldiers, some of whom come from Alaska, will be sent to Iraq next week.

who和whom的区别

1.who和whom都是人称代词，who为主格人称代词(Subject Pronoun), whom为宾格人称代词(Object Pronoun)

2.whom是who的宾语格式，只能做宾语。

3.who可以做主语,又可以做宾语。

注意：关系代词whom在口语和非正式语体中常用who代替,可省略

简单点说就是：Whom只能出现在从句里面或是介词（如to,from,at,of..）后面。