Might I enquire why you have not mentioned this until now?

请问你为什么直到现在才提及此事呢？

《牛津词典》

It's very late now—why don't you sleep over?

现在已经很晚了—为什么不就睡这儿呢？

《牛津词典》

Now you know why I never miss a lecture.

现在你知道为什么我从不错过一节课了吧。

youdao

(THUNDER CRACKS) Okay, now I see why you need the thunder.

VOA: standard.other

Let's hear first, now we need to begin to investigate the reasons why you think it's the right thing to do.

我们先来听听大家的说法，探究一下为何,你们会认为这是正确的选择。

耶鲁公开课 - 公正课程节选

- And we can think about why -- essentially we have fluorine and now we're adding another electron. So you can picture that fluorine is going to get larger in this case And that would be true for all of the negatively charged ions.

我们可以想一想这是为什么-,本质上来讲我们现在给氟原子加上了,另外一个电子,因此大家可以想象在这种情况下氟将变大,而且这对于其它负离子也是成立的。

麻省理工公开课 - 化学原理课程节选

And now you see why President Barack Obama rarely risks speaking without his traveling teleprompter.

FORBES: Newt Gingrich Highlights Republican Futility On Spending

"If these cost a lot in a restaurant, now you know why, " Galletta said.

NPR: An Unexpected Delight: Fried Olives in Italy

You can see now why they were jumping for the lifeboats of Atlantic and English Premier Leagues.

BBC: Chick Young's view