Some drugs can be a problem because they suppress the immune system.

VOA: special.2009.04.14

But for people who have a difficult time controlling their movements, this little navigational issue can be a really big problem.

VOA: special.2011.04.18

He said it is a serious international problem that should be addressed broadly and can not be solved entirely by military means.

VOA: standard.2009.04.13

Delegates here say climate change is a global problem and can only be solved globally.

VOA: standard.2009.08.31

According to Ben Urbonas, president of the Urban Watersheds Research Institute, these nutrient contaminants tend to be more of a problem in closed water systems,like lakes, where concentrations can build up.

VOA: standard.2010.08.04