One more challenge. And that is keep going.

VOA: special.2010.05.28

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

Sometimes they challenge and contradict one another, but they are not best seen as linear, as telling a neat, linear story about Israelite religion flowering and fading.

有时候它们相互对质或矛盾，但它们从未被当作线性结构，整洁有序的故事,关于以色列宗教的兴盛与衰落。

耶鲁公开课 - 旧约导论课程节选

"Every fish we take out there is one less fish to challenge the electric barrier further upstream yet."

VOA: standard.2010.07.19

Now for the hacker edition, if you are feeling up to a bit more of a challenge you'll find that when you run the game, one it's not all that hard to use some ASCII art just make it a little fancier as the teaching fellow who implemented this solution did.

对于升级版，如果你能应付更大的,挑战，你会发现当你在玩这个游戏时，用一些字符画把它做得,比那些教学人员做的更有新意,并不是那么困难。

哈佛公开课 - 计算机科学课程节选

Declarations,commitments and speeches don't feed hungry people, He says the scale of the challenge is significant. There are more than one billion poor and hungry people in the world today.

VOA: standard.2010.03.29

One of the most closely watched cases this term will be heard early next year when the high court considers a challenge to gun control laws in the city of Chicago.

VOA: standard.2009.10.05