The girl to 空 I spoke just now is my sister.空里为什么不能填who或that?

问题描述:

The girl to 空 I spoke just now is my sister.空里为什么不能填who或that?
who或that也可以在定语从句作宾语为什么在这里就不行,只能填whom.

to whom
有介词to,那就是说后面填的代词必须是宾格人称代词,这样才能做介词宾语!