look、expression都有表情、臉色的意思。
但，"Look" is an expression that you make with your eyes or face.（"Look" 是指妳用妳的眼睛或面孔做的表情。）
"expression" is a look on someone's face that shows what they are thinking or feeling.（"expression" 是指表情顯現在某人的面孔上，顯示他們的想法或感覺。）