The standard is a little higher, so the group performs more difficult pieces.

"It was the most difficult piece I had ever worked on," he explained.

He made it seem one huge and incredibly difficult piece of thinking.

Defense lawyers say that will be a very difficult piece of evidence to explain away.

I did the 'Ring' and all the big difficult pieces.

He also allowed to carry out a very difficult piece of surveillance.

In the middle of working on a difficult piece I can almost feel my ears grow, he said.

It was a very difficult piece of work, but you were always prepared to cooperate.

They have certainly carried out a complicated and difficult piece of work.

This was going to be a difficult piece of work, and she needed to concentrate on it.