expression, suru verb (irregular)
look displeased; frown; scowl; look grave; look serious
Describes a facial expression showing displeasure, worry, or deep thought. Often used when someone is troubled or concentrating hard.
See also: 難しい
彼は難しい顔をして考え込んでいた。
He was deep in thought with a grave look on his face.
My mother frowned when she saw my report card.