why didn't 可以改成why not 我知道why don't you =why not但题目是过去式,这样可以替换吗

why didn't 可以改成why not 我知道why don't you =why not但题目是过去式,这样可以替换吗
why didn't 可以改成why not
我知道why don't you =why not
但题目是过去式,这样可以替换吗

why didn't 可以改成why not 我知道why don't you =why not但题目是过去式,这样可以替换吗
可以吧.

应该可以

可以

why didn't you+动词=why not+动词