And their last mission had been the most challenging one of all.

The decade was known for social change and challenging of traditional ideas.

Some say it's by far the more challenging of the two.

The Legends course is considered to be the more challenging of the two.

The pheasants they hunt, however, are not the most challenging of game.

The higher difficulty levels are considered by some players to be the most challenging of any music game.

She calls the role the most challenging of her career: "I play older than myself.

Section 73 lays down the rules for the challenging of election results in court.

Perhaps most challenging of all, though, is having to balance school and work.

Until and unless that happens, I can't do any challenging of my own.