They were focused directly upon the door of the building.

Her hand went back up to tap upon the door.

No one knocked upon the door to see if he was hurt.

A knock upon the door, he told himself, could mean nothing else but trouble.

A moment later there came a knock upon the door.

While the talk was still going on there came a knock upon the door.

The tap was from a hand, and low down upon the door, as if it were given by a child.

I felt it, the little knock upon the door of the heart.

"Yet we must knock upon the door if it is to be opened to us!"

Then one day there came a light scratching upon the door.