What is that which you have just stuffed into the plastic cup?此处which的用法?

问题描述:

What is that which you have just stuffed into the plastic cup?此处which的用法?

你刚刚塞到塑料杯子里面的是神马东东?
which是关系代词,引导定语从句,修饰并指代that.主句是What is that?which 能用哪个词代替?which不能代替。本来这样的定语从句which和that可以互换的,但如果先行词是that,再用that引导定语从句就会很怪,所以只适合用which.