I've had her out a couple of weekends and the engines have been humming.

The engine hummed to life even while the door was closing again.

In the distance, he could hear the ship's powerful engines humming.

I still don't get it, he thought, while under and behind him the engines hummed softly into life.

He dropped into the driver's seat; set the engine humming.

The engine hummed to life and Alex pulled out of the parking lot.

The battalion's many engines were humming and singing all over the village.

It was a big, heavy, quiet car, but Mark could hear the engine humming very softly somewhere far away.

The cargo plane had been rolled out and its engines were humming.

An entrepreneurial spirit that keeps the city's economic engine humming?