除了介词+ WH =关系副词这个用法，其他时候是不是只是美化句子把介词提前
this is the man that my teacher is talking with
为了梅花句子就是 this is the man with whom my teacher is talking
就是单纯的把句子里的介词提前然后找个关系代词？？
可是为什么不把介词放在句子里，干脆不提前，省事
比如
this is the car which he spend on 25 w is made in china
不用变成this is the car on which .....