一般来说，有人对自己微笑时，大多数人都准备好以微笑回应。

Most people, generally speaking, are ready to smile back when they are smiled at.

youdao

当学生们自由地模仿微笑时，他们的判断不受售货员行为的影响。

When the students were free to mimic the smiles, their judgments were not affected by what the salesclerk was doing.

youdao

当你第一次和别人说话或微笑时，记得对自己说：“我做到了！”

After you begin to talk to someone or smile at someone for the first time, remember to say "I did it! " to yourself.

youdao

So, he writes: To the psychologist alone can such questions occur as: Why do we smile when pleased and not scowl?

他这样写到：,对哲学家本身说,会出现这些问题：,为什么开心时我们微笑而非皱眉？

耶鲁公开课 - 心理学导论课程节选

Then when a stranger approaches or someone else approaches there they'll tend to give more of a greeting smile.

当陌生人或其他人接近时,他们是问候式微笑。

耶鲁公开课 - 心理学导论课程节选

But another clue is the sort of smiles they give when they see each other when they walk into the lab.

但另一个线索是他们给出的微笑,当他们走向实验室时碰到对方。

耶鲁公开课 - 心理学导论课程节选