If you try to imagine a smile with no body at all, it can't be done. Why?

如果你要相信一个没有身体的微笑,那是根本做不到的 为什么呢

耶鲁公开课 - 死亡课程节选

So, if you smile at somebody, and you just hate their guts but you want to smile at them, it's--unless you're quite gifted it's difficult to fake a really good, really happy smile.

所以，你对某人微笑，你很讨厌他们，但你要对他们微笑，除非你很有天赋,很难去假笑，伪装真正的微笑。

耶鲁公开课 - 心理学导论课程节选