Don't smile very often.

不要常常微笑。

youdao

Have you ever wondered why being around children who smile so frequently makes you smile very often?

你有没有想过，为什么身处在经常微笑的孩子身边，也会让你经常微笑？

youdao

My mother is a doctor. She is very kind to me, and there is always smile on her face. She often helps me with my lessons.

我妈妈是一位医生。她对我很好，她的脸上总是带着微笑。她经常帮我学功课。

youdao

While Obama was talking, Romney more frequently had an openness in his visage, often with a slight smile on his face and very soft eye contact. (Some may view the smile as a smirk, but that is the confirmation bias at play.) I noticed this frequently in the Republican presidential debates.

FORBES: Three Methods of Persuasion You Can Copy From Obama and Romney (and one from Joe Biden that you should not copy)