为什么不闭上你的嘴！

Why don't you shut your big mouth?

《柯林斯英汉双解大词典》

为什么你不试试说服他？

Why don't you have a try at convincing him?

《牛津词典》

你为什么不征求他的意见？

Why don't you ask him for his advice?

《牛津词典》

And why is that? Within the perspective of Milton's free-will theology, sin can't exist as an external reality.

为什么呢？从弥尔顿自由意志的学说的角度来看，原罪是不可能以永久现实的形式存在的。

耶鲁公开课 - 弥尔顿课程节选

But for me, I like to look at something and just say, "I like this. I don't really know why though."

但对我来说，我喜欢看着某个东西，然后说，“我喜欢这个。但我也不知道为什么。”

关于现代美术 - SpeakingMax英语口语达人

And I don't know why, but since time immemorial that is the way computer scientists have drawn trees.

叶子是在最下面的，我不知道为什么,但从记事以来他们就是这么画树的,这也许就是为什么我们。

麻省理工公开课 - 计算机科学及编程导论课程节选