Kids in both groups then had the opportunity to try a challenging task, with the promise they could learn from it.

"I think it's going to be a very challenging task."

Another challenging task is the problem of social and environmental costs, which are not included in the actual price.

The authority's next chief executive is likely to find challenging tasks ahead.

Drawing the line between life and death is one of society's most challenging tasks.

Team members support one another through challenging tasks and difficult periods.

This is a challenging task for the governments of developing countries.

For instance, a child may talk him- or herself through a challenging task.

Madam President, we have a very challenging task before us.

We call on everyone to help us with this challenging task for the six months ahead.