It has set us back in so many respects that I'm not sure how long it will take for us to catch up.

我们在很多方面都被延误了，不知道需要多久才能赶上。

《柯林斯英汉双解大词典》

How long it will take by subway?

坐地铁要花多长时间？

youdao

Can you estimate how long it will take to build?

但你能估算出构建它需要多长时间吗？

youdao

And mixed economic signals continue to call into question how long it will take for the country to emerge from recession.

VOA: standard.2010.01.06

The how long will it take you diets?

还有关于节食周期的

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

The secretary general would not say when the transition might start, how long it will take, or when it might be possible to start reducing the NATO troop commitment.

VOA: standard.2009.10.23

Is this how long it will take us to realise the democracy of tribal equality?

CNN: In the Field

It's not clear how long it will take Carter's case to move through the court system.

CNN: Virginia deputy fights his firing over a Facebook 'like'

" Now that he has sought asylum in Ecuador, "You don't know how long it will take.

CNN: Assange to be arrested if he leaves embassy, police say