请写个句子帮我理解下面这段话！

来源：百度知道 编辑：UC知道 时间：2024/06/30 09:22:01
如果which在从句中作“不及物动词＋介词”的介词的宾语，注意介词不要丢掉，而且介词总是放在关系代词which的前边，但有的则放在它原来的位置，请写个句子，让我了解这个什么意思！

I want to find the pen with which I wrote that letter
这里的with不能去掉，可以放在which前面或者后面
I want to find the pen which I wrote that letter with

This is the house in which I live.
which指代先行词house做介词in的宾语