我在想，既然我马上就会再吐，那为什么还吃呢?

I figured, why eat when I was going to puke it up again?

《柯林斯英汉双解大词典》

不管我做什么都没有区别，那为什么还要费心去做呢？

Nothing I do makes any difference anyway, so why bother?

《柯林斯英汉双解大词典》

那为什么不去国外工作一两年呢？

Then why not work abroad for a year or two?

youdao

The performance of family conversation is like acting, and that is why Zooey impersonates Buddy; he's acting.

家庭对话的表现则像是表演，那是为什么左伊模仿巴蒂，他在表演。

耶鲁公开课 - 1945年后的美国小说课程节选

And that's not very English and I think that's why he is a bit more shocking, not on English television,

那不是很有英国范儿，我想这就是为什么他有一些骇人的，不是在英国电视上，

认识戈登•拉姆齐吗？ - SpeakingMax英语口语达人

So that would probably be de Broglie's answer for why, in fact, we're not observing the wavelength behavior of material on a day-to-day life.

所以那就可能是德布罗意关于,为什么我们无法再日常生活中,观测到物质的波动行为的答案。

麻省理工公开课 - 化学原理课程节选