How long can you balance on one leg?

你单腿能站多久？

《牛津词典》

"But how long can you stay in the house?"—"I don't know. It depends."

“但你能在这屋里待多久？” — “不知道，这要看情况而定。”

《柯林斯英汉双解大词典》

The key is , how long can the federal government control the inflation rate?

关键在于联邦政府对通货膨胀率的控制能维持多久？

《牛津词典》

How long can she keep it a secret,anyway? Jennifer Lopez gave birth to twins a couple of years ago and drew on her own experiences to play Zoe.

VOA: standard.2010.04.30

As time increases, the angle increases and we can ask, "How long does it take for the particle to come back to the starting point?"

这个角度随着时间在增加,我们会问,"质点需要多长时间,才能转到起点"

耶鲁公开课 - 基础物理课程节选

I need to know how long, so that I can let my roommates know.

我得知道大概有多久，这样我就可以告诉我的室友们了。

How long实战 - SpeakingMax英语口语达人

How long can Valero and its larger rivals ExxonMobil and ConocoPhillips surf this wave?

FORBES: On The Cover/Top Stories

And how long can banks afford to ignore the minefields of insight from social media?

FORBES: Now that data's going really big, what's next?

But how long can that survive given Wales' failures to make the fixtures a competition?

BBC: Tri-Nations aura arrests Wales development