why not还是why don't?这两个短语到底什么时候用啊?

why not还是why don't?这两个短语到底什么时候用啊? why don't we =why not 还是why don't you=why not why not 同义词是 why don't you 还是 why don't you do why not 和why don't 有什么区别啊! why don't和why not Why don't you+...why not +. why not是否等于why don't we?（why not后面用加together吗) why don’t you=why not还等于什么?两个空!麻烦大家答答. why not后加do还是to do?why don‘t you 后面呢? why don't you still come 还是why do you still not come? 为什么你不喜欢他 翻译到底是Why you don't love him 还是Why don't you love hi why not是否等于why don't we