何不hébù用反问的语气表示应该或可以,意思跟‘为什么不’相同{[used in rhetorical questions to express ‘should’ or ‘could’] why not}: 既然有事,～早说?{If you had something on your mind, why didn't you say earlier?}|他也进城,你～搭他的车一同去呢?{He's also going into town, why don't you get a lift in his car?}