It is a long-term endeavor and we both are united to fight against this endeavor, which is challenging our way of life and wants to challenge the way of life with the world."

VOA: standard.2009.05.13

What we've seen is a testing of the system -that we have regulatory requirements, that banks have enough capital -but this regulation is challenging because it's being stressed right now.

我们列举的这些案例都是对银行体系的考验,我们需要加强监管,以确保银行有充足的资本,但监管确实是一项艰巨的任务,因为现在面对的压力更大了

耶鲁公开课 - 金融市场课程节选

We're still close enough to the summer that the air is not just filling us up with extra static electricity, so it's a little more challenging here.

我们现在离夏天更近了,这样空气中不总是,充满额外的静电，所以这时做实验,会有一些挑战性。

麻省理工公开课 - 化学原理课程节选

He says he likes that the music is more challenging than what he plays with his school orchestra.

VOA: special.2010.06.21

I think this is as good list so let's go and think about what might be a little bit more challenging.

我想上面这些都是很好的例子,接下来我们思考一些更有挑战的问题

耶鲁公开课 - 生物医学工程探索课程节选

"It is extraordinarily challenging and that is why Calderon is fighting a war on multiple fronts,"

VOA: standard.2009.12.18

He makes it clear that utility is the only standard of morality, in his view, so he's not challenging Bentham's premise. He's affirming it.

明确指出功利是道德的唯一标准，在他看来，他并没有质疑边沁的前提，而是肯定此观点。

耶鲁公开课 - 公正课程节选

Making the transition from high school to college is often a challenging experience.

VOA: standard.2009.12.04

Cultural access is perhaps even more challenging.

文化接触可能更有挑战性。

麻省理工公开课 - 媒体、教育、市场课程节选

But the acquisition of radioactive material for a so-called 'dirty bomb,' which is radioactive material that is dispersed with a conventional explosive device, that is not that challenging.

VOA: standard.2009.05.01

"That character piece is the foundation. As we like to say, when you are put in very challenging environments, like the southern Helmand province of Afghanistan, or recently in western Iraq.

VOA: standard.2010.04.06

"The market is definitely very, very challenging. Our airline customers are feeling the pain of the situation and of the environment but clearly we're starting to see some signs of stabilization in the market in terms of the economy,".

VOA: standard.2009.06.16

"The prime minister is leading Greece through challenging times, but as I told him during our meeting in the Oval Office today, whether in good times or in bad times, the people of Greece will always have a friend and a partner in the United States."

VOA: standard.2010.03.11