There's no vision to it." "There's no goal. There's no challenge." "Obviously there are a lot of people that are unhappy about the potential of altering the future of space flight."

VOA: standard.2010.04.15

Also, shows you something about the challenge of it, because we are susceptible to attack from lots of different kinds of microorganisms.

同样也向你们展示这其中的一些挑战,因为我们也容易受到,各类微生物感染的危害

耶鲁公开课 - 生物医学工程探索课程节选

The challenge is about all of them.

挑战在于包括所有这些。

麻省理工公开课 - 媒体、教育、市场课程节选

For Garson,it has been a challenge to put aside his concerns about Haiti, and focus on football and the most important game of his career, but he has a simple message to Haitians.

VOA: standard.2010.02.04

"The EPRDF has discussed with parties that seem to approve or endorse its lines, not the serious parties that do challenge the EPRDF and do have serious issues about the political space in the country,"

VOA: standard.2009.11.01