Why not 和Why don`t的区分“Why not give your teacher some flowers?" 此句中为什么不用Why don`t?

问题描述:

Why not 和Why don`t的区分
“Why not give your teacher some flowers?" 此句中为什么不用Why don`t?

Why don't 后加人称、谓语,Why not 后直接加动词.如:
Why don't you take a bus?
Why not take a bus?