He tried to draw the characters that he saw with unusual expressions on their faces.

Brad looked a little chagrined, an unusual expression for him.

It was a human expression that meant "interesting" and "unusual" and several other things.

This was an unusual expression, even for this type of creature.

For a moment there was an unusual expression in Spock's eyes-respect?

Photos with unusual expressions and squinting will not be accepted.

Reading the file caused his face to assume an unusual expression of humorous doubt.

His easygoing face, though, was wearing an unusual expression of strain and concern.

This was such an unusual expression of judicial sentiment that I had always wondered where it came from.

He put a hand on her forehead, an unusual and disturbing expression on his face.