He stopped and began to swear quietly, in a completely different tone of voice.

He let go of the breath he'd been holding and swore quietly under his breath.

A minute later, he began to swear quietly under his breath.

The professor swore quietly and the young surgeon looked at him in surprise.

Bird Dog swore quietly to himself, wishing he'd paid more attention to the last intelligence brief.

Bird Dog glanced down at the fuel indicator and swore quietly.

He looked out over the gleaming city, glanced again at the watch face in his wrist, and swore quietly.

Hansen swore quietly, trying to gather up enough strength to get out of his armor.

Kelly swore quietly, looking at the deep cut on his left hand.

He quietly swore never to try to save anyone else, particularly from addictions, they said.