关于英语定语从句中的介词+关系词的问题

问题描述:

关于英语定语从句中的介词+关系词的问题
This is the pilot by whom my son was saved.这句可不可以改成This is the pilot who my son was saved by.
为什么呢?
定语从句什么时候介词提前

原则就是不能有歧义,不能改变原来的句意.尤其是当引导词充当介词的宾语时,提前是习惯.如:
The book from which I have learned a lot was from my uncle.
你给的句中,who/whom是by的宾语,习惯上不分开.