She says people might have difficulty completing an activity if they cannot expect some kind of reward in return.

VOA: special.2009.09.29

But small businesses have been hit hard by the recession and now the difficulty in getting loans.

VOA: special.2009.12.18

And scientists often have difficulty explaining what they do in language the public can understand.

VOA: standard.2010.05.04

And,he notes humanitarian organizations have great difficulty in reaching them with much needed assistance.

VOA: standard.2009.09.26