Robert knocked the cup away with the back of his hand.

She stood to one side of the door and knocked with her left hand.

When there is no response, he knocks again with the same result.

He was knocked against the other wall with a force that almost broke his back.

I knocked at the door of communication with the front room.

A minute or so later she knocked the door back open with her shoulder.

An hour later a security guard knocked on our door with a letter.

I had to knock on their door with my elbow.

He was knocked dizzy with about five minutes left in the game.

Then she reached out and knocked on the rock with a stick.