Why not have the dish of the day?
為什么不吃今天的精選菜？
Why not write to her?
為什么不給她寫信呢？
Why not tell her you're quitting and have done with it?
為什么不告訴她你打算辭職，盡快把這件事了結了呢？
I didn't want a part in the play, then I thought ─ stuff it ─ why not?
我本來沒想在劇中扮演角色，然后又一想——管它呢——干嗎不演？
Why not spoil yourself with a weekend in a top hotel?
為什么不到頂級飯店度個周末，讓自己享受享受呢？