定语从句中,如果关系代词作宾语的话可以省略,比如说：
I like the book (that/whcih) you bought for me.
The man (who/that/whom) he is talking with is from the USA.
介词提前就不能省略了.The man with whom he is talking is from the USA.这里就不能省了.
不懂追问.省略who is 后就不是定语从句了， 是非谓语动词作定语了！明白了吗？