whom 的语法

定语从句中先行词为物时用that 或者which
先行词为人时用that或者who
This is the book which I bought yesterday.
I don;t like the man who I saw last night.
whom用于先行词在从句中作宾语时，一定要记住是在从句中作宾语！This is the man whom I talked with the other day.

上句who也可以用，但介词之后只能用whom

This is the man with whom I talked the other day.
此处只能填whom

whom 是宾语，只有名词属性,在介词之后也一般用Whom
例如
Whom are you talking about?
By whom is the letter signed?

Which 用于指代物或人，有名词和形容词的性质

This is my copy ,which is yours ?(单数，作定语)

which of the stories do you like best?
(单数，作宾语)

which of you will go with me (单数，作主语)

who 是主格，名词性质
1 用于疑问句
who put that light out

2修饰疑问句
who could blame you ?

自己买本语法书看看，会更有帮助