After an hour of deep concentration, he called his staff together.

How about the issue of concentration, especially in the media?

The old man seemed to have lost some of his own concentration.

It took a great deal of concentration for me to be able to stand up.

A small amount of concentration, and I knew they were still dead to the world.

For a moment a look of concentration passed over his face.

This is the point of concentration for the whole town.

It took her a few minutes of concentration before she could start.

The time of concentration usually last on average about ten minutes.

And, after giving the subject a good deal of concentration, I knew what had to be done.