to move your eyebrows close together in an expression that shows you are feeling worried or serious, or are thinking carefully about something 皱眉(表示担忧、严肃或认真思考)
[I/T]if your face or a part of it sets into a particular expression, or if you set it into a particular expression, you have that expression on your face (使)(脸上)凝固(某种表情)
His face set into a determined expression as he read the letter. 他看信的时候神色坚毅。