Until when can you stay?

你可以待到什么时候？

《牛津词典》

When can I see you?

我什么时候可以见你？

《牛津词典》

When can we go for a swim?

我们什么时候可以去游泳？

《柯林斯英汉双解大词典》

For example, lightning can create tubes of glass when it strikes sand that has the right combination of minerals.

VOA: special.2009.09.16

And when you have an optimal substructure and the local solutions overlap, that's when you can bring dynamic programming to bear.

当你得到一个最优子结构,但局部解决方案有重跌时，你就可以引入动态编程,来解决这个问题了。

麻省理工公开课 - 计算机科学及编程导论课程节选

so at the moment when I can't go back to see her, I go to training academies.

所以我不能回去找她的时候，我就去培训学校。

做头发是免费的 - SpeakingMax英语口语达人

Twice in the past nine months, the Canadian establishment has rallied round to prevent what it perceived as an unwanted takeover of a strategically important interest - which is the sort of thing we haven't seen in the UK since... well I can't remember when.

BBC: Is Canada hurt by saying no to foreign bids.......

One session asks whether the U.S. can stay competitive when technology innovation is being embraced by every other nation.

FORBES: Here Comes the Techonomy Conference

Go to them and tell them you have a problem, why you have it, and make a proposal to pay what you can when you can.

BBC: Pile of coins