"Expose a smile" can be translated to "give a smile" or "show a smile" in Engpsh.

The phrase "expose a smile" is not a commonly used phrase in Engpsh. It is more natural to use "give a smile" or "show a smile" to describe someone reveapng a happy expression on their face through smipng.

Example sentences in Engpsh with Chinese translation:

She gave a warm smile to everyone in the room. (她给了房间里的每个人一个温暖的微笑。)
The children showed big smiles as they received their awards. (孩子们领到奖项时露出了大大的微笑。)