问题补充：
which的用法（定语从句）在什么时候,定语从句中,只用which而不用that?
答案：
只用which
1 关系代词作介词宾语,即 介词+关系代词,指物只能用which
Last night I had a dream in which I became a Nobel Prize winner.
2 非限制定语从句中,指物只能用which,亦可指整个前面的句子.
He reads English every day,which does good to his English study.
======以下答案可供参考======
供参考答案1:
在指物的句子中介词后不能用that,而用which.
