this is the train _____定语从句this is the train (on which) we will go to Beijing.为什么不可以用by which?不是可以表方式吗?先行词是train还是the train?有什么区别?

问题描述:

this is the train _____定语从句
this is the train (on which) we will go to Beijing.
为什么不可以用by which?不是可以表方式吗?
先行词是train还是the train?有什么区别?

by train
on the train

先行词是the train,所以只能用on which

原句应为:We will go to Beijing on the train.
而不是by the train啊,所以在转成定语从句后,不可以用by which