Professor Paul Bloom: I don't know if that's--The question is, "Is there a difference between smiling with your teeth versus just your lips closed?"

我不知道是否，问题是，微笑露齿与不露齿有不同吗“

耶鲁公开课 - 心理学导论课程节选

Press your lips together with the corners straight or down.

把嘴唇并在一起，嘴角成一条直线，向下。

耶鲁公开课 - 心理学导论课程节选

Raise the corners of your lips back and up, please.

请把你的嘴角下扬，上抬。

耶鲁公开课 - 心理学导论课程节选