He was marvellously cool again, smiling as if nothing had happened.

他又变得出奇的冷静，微笑着，似乎什么都没有发生过一样。

《柯林斯英汉双解大词典》

For example, if a student smiles at Bill, he responds by smiling back.

例如，如果一个学生对比尔微笑，他也以微笑回应。

youdao

If you are at a party, you'll find everyone smiling happily and loudly.

如果你在一个聚会上，你会发现每个人都在开心地大声笑着。

youdao

She is smiling. If you know the story, her smile clearly says: "I won."

VOA: special.2010.04.25

I think both of us would love to see your smiling faces, or at least your faces, even if you're not smiling at us every day.

我觉得我们俩都想,看到你们微笑的脸，或者至少是你们的脸，即使你们不是每天都朝着我们俩笑。

麻省理工公开课 - 计算机科学及编程导论课程节选

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

What's unclear is whether smiling reflects a person's overall happiness or if the act of smiling contributes to that happiness.

WSJ: Stress-Busting Smiles

The system also inspects images to see if people are smiling or looking directly at the camera lens.

BBC: NEWS | Technology | Camera specs take candid snaps

Marco Iacoboni, a lab director at the UCLA Brain Mapping Center, says when people see a smile, so-called mirror neurons fire in their brain and evoke a similar neural response as if they were smiling themselves.

WSJ: Stress-Busting Smiles