why not 与shall we可以互换

问题描述:

why not 与shall we可以互换
Why don't you go skating in Korea this winter?
_____________go skating in Korea this winter?

不能互换!
shall 用来征求建议,比如我们两个,征求老师建议,
shall we go now?
why not = why don't you一般用来给对方提供建议.