关系代词whom,which,that在限制性定语从句中作动词宾语或介词宾语,而该介词由位于从句末尾时才省略,

在定语从句中,关系代词that ,which,whom 在定语从句中作宾语宾语时可以省略,例如
He found the book ( which/that ) he lost yesterday.
This is the boy (whom ) I talked of the other day.
如果定语从句中出现把从句中的介词提前到关系代词which和whom 之前,这时候关系代词which和whom 作介词宾语时,关系代词不能省,介词提前关系词不能用that .
This is the pen ( which /that) he wrote his composition with.在这个句子中which/that可省.
This is the pen with which he wrote his composition.这个句子中 which 就不能省.
I like the boy (whom ) we played football with.
I like the boy with whom we played football .

你说的省略我没懂，在这里就给你解释一下子这些歌词的区别吧，希望能帮你
一般情况下，whom都是在从句中作宾语的时候用,就是定语从句中本来该用表示人得关系代词WHO的但是由于在句中的成分比较特殊是宾语，所以就用whom.例如： I did not recognize the man whom I once dated with,这里面whom就是作的介词with的宾语，而whih呢一般就是介...