关系代词whom, which在定语从句中作介词宾语时，可以和介词一起放在先行词与定语从句之间。

in which

That is the placeI lived for five years.

which / that

=That is the placeI lived in for five years.

那就是我住过五年的地方。

for whom

Mr Zhang is the manI am looking.

who / whom / that

=Mr Zhang is the manI am looking for.

张先生就是我正在找的那个人。