我们在很多方面都被延误了，不知道需要多久才能赶上。

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

《柯林斯英汉双解大词典》

——安需要多久才能完成她的作业？ ——一小时以后。

—How soon will Ann finish her homework? —In an hour.

youdao

黄石的第一条有轨电车线要多久才能完工？

How soon will the first tramcar line be finished in Huangshi?

youdao

And the obvious question I could start with is, and suppose I ask you, how long does the algorithm implemented by this program take to run?

我开始这个话题的第一个问题是，假设我问你，由这个算法实现的程序大概,要运行多久才能给出答案？

麻省理工公开课 - 计算机科学及编程导论课程节选

How long do you have to be around a person to see him, to estimate how good a lecturer that person is?

你要看一个人多久，才能评估出他讲课有多好？

耶鲁公开课 - 心理学导论课程节选