英语问题。

B，表情。

look、expression都有表情、脸色的意思。

但，"Look" is an expression that you make with your eyes or face.（"Look" 是指你用你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" 是指表情显现在某人的面孔上，显示他们的想法或感觉。）