定语从句中的介词前移到关系代词前,构成介词后面紧跟关系代词(介词+关系代词),那么这个关系代词两种情况:关系代词指人时只用whom,指物时只用which. This is the famous writer (who/whom/that) the novel was written by. This is the famous writer by whom the novel was written .
I don't know the man to whom the teacher is talking . 本来的句子应该是 I don't know the man who the teacher is talking to. 第一个句子是把to 提前到关系代词前,who就要用她的相应的宾格whom 来代替。