He finally was set down on a cold, hard surface, unable to move.
We run out of hard surface in less than a minute.
As nothing happened, he put out his hand, and felt a cold, hard surface.
He will never be able to sit on a hard surface again.
More generally, any hard surface can act as a sound board.
All three hit the hard surface and covered their heads.
Not everybody could stand lying still on a hard surface for long.
For a time, he lay on the hard surface before opening his eyes.
He was looking at the hard surface of the rock.
Be sure to throw it with some force against a hard surface.