He remembered frowning blackly at the monitor as he'd tried to work that out.

"I'm beginning to suspect you're just inventing these examples," Anderson said, frowning blackly.

Del frowned blackly.

The door was flung open and Tonnerre stood there frowning blackly.

"Aurigans are impossible," Carigana announced, frowning blackly at the departing figure.

The chief engineer came forward; and it worried Morton to note that he was frowning blackly.

He frowned blackly.

DuQuesne frowned blackly in concentration.

The sergeant was looking at the captain, who was frowning blackly at O'Leary.