He knocked gently on the door, but no one answered.
I knocked gently at his door; there was no answer.
He knocks gently on the window and she opens her eyes with a start.
A few seconds later, she knocked gently on the door.
He knocked gently, and after a few minutes heard her walking down the hall.
He knocked gently, then eased the door open and took but a single step inside.
John went round to the back and knocked gently at the kitchen door.
They were interrupted by someone knocking gently on the door.
Suddenly the man stopped, knocked gently on a door and entered.
I knocked gently at the bathroom door to be sure he wasn't inside.