But it is a challenge that needs to be addressed immediately before it is too late,".

VOA: standard.2009.04.24

Mr.Obama admits that coordinating the activities of 16 U.S.spy agencies is a major challenge, but he believes Clapper will be able to do so.

VOA: standard.2010.06.05

"It is a challenge after just a few months of implementation to be able to speak with confidence about when these things will occur,"

VOA: standard.2009.09.04

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

"When you put that all together it suggest that we are going to need something like 50 percent more, perhaps 100 percent more, food from our existing land and that is a very significant challenge and we believe we need to be thinking seriously about that right away,"

VOA: standard.2009.10.21