“which”的用法是which的用法：
1、(用作疑问代词)哪一个,哪一些
Which is my seat? 
哪个座位是我的? 
2、(用做关系代词)那一个,那一些
He also had a gun with which to defend himself. 
他还有一把自卫用的枪。 
3、（用作疑问形容词)哪一个,哪一些
Which university did you go to, Oxford or Cambridge? 
你上过哪所大学?牛津还是剑桥? 
4、(用作关系形容词)这个,这些
The doctor told him to give up smoking, which advice he took. 
医生叮嘱他戒烟,他接受了这一忠告。



扩展资料：
词义辨析
that和which都可引导定语从句,但以下情况引导定语从句的关系代词只能用that不能用which。
1、当先行词是all, everything, nothing, anything, little等不定代词,或被first, last, only, few, much, some, any, no等词修饰时,应该用关系代词that,不用which。
2、当先行词为形容词最高级所修饰时,关系代词用that不用which。
3、当并列的两个先行词分别表示人和物时,要用关系代词that而不用which。
4、在强调句型“It is〔was〕...that〔who〕...”中,只能用that,不能用which。