you will find thismap of great value in helping you to get round london.in为什么不能用when

问题描述:

you will find thismap of great value in helping you to get round london.in为什么不能用when

其实可以, 但要这样说:
You will find this map of great value in helping you when getting around in London.
或更简洁:
You will find this map very helpful when getting around in London.