Another problem is access. Connecting informal communities to the city's water pipeline is a challenge because many are living on the land illegally.

VOA: standard.2010.08.04

And so if you choose to elect the hacker edition of this week's problem set the challenge will be to figure out not only how to implement the game but how to implement a solver for the game.

因此，如果你选择这周的应用题目为升级版,那么你将面临的挑战,不仅是如何实现这个游戏，而且,要实现此游戏的解决方法。

哈佛公开课 - 计算机科学课程节选

Of course, the particular problem of Ireland, the challenge of Ireland as I suggested earlier, has an awful lot to do with that.

特别是爱尔兰的问题,我之前提到的,来自爱尔兰的挑战,也与之也有很大关系

耶鲁公开课 - 欧洲文明课程节选

That's one challenge and we'll talk about ways to think about engineering approaches to solve that problem.

该问题一直很具挑战性,我们会讲到,如何用生物医学工程的方法来解决它

耶鲁公开课 - 生物医学工程探索课程节选

The other threat is eonomic, and all the economic issues are tied in my judgement, to the same core problem which is the long-term fiscal challenge that this country faces.

另一个威胁是经济方面的，我认为所有的经济问题,都和一个核心的问题分不开,就是我们国家面临的,长期财政挑战。

普林斯顿公开课 - 国际座谈会课程节选