He says the biggest challenge is jobs the disabled have the lowest employment rate of any minority group in the country.

VOA: special.2009.08.15

What it meant was that in principle, your power was greater than any challenge that could come from those underlings, those craven reptiles in your imagination over whom you ruled.

这意味着在原则上,你的权利大到,不会受到属下的任何质疑,在你的眼里他们应该是低声下气的应声虫

耶鲁公开课 - 欧洲文明课程节选

But you know, I understand it's a challenge when you're coming from a language that doesn't have any concept of an article.

但是，我能够理解当你的母语没有冠词的概念时，它将是一个挑战。

经常犯的失误 - SpeakingMax英语口语达人

Writer-director Richard Linklater believes any moviemaker would be daunted by the challenge of telling the story of the man behind the great American film Citizen Kane;

VOA: standard.2009.12.17

And sometimes had them killed if he had to if he thought that's what he should do, because there wasn't any sort of challenge to his authority.

如果有必要,他甚至会杀掉那些碍事的议员,因为没有什么可以挑战他的权威

耶鲁公开课 - 欧洲文明课程节选