"Mr. Li, this is Miss Wang."
In China, 小姐 is less used to mean young lady because the meaning prostitute took over the original meaning; 女士 (nǚshì) is used instead. One can still use 小姐 as a title (see the usage example). Do not use 小姐 to call a waitress, but use the neutral word 服務員／服务员 (fúwùyuán) for that instead. The definition may revert somewhat in the distant future (becoming similar to the word 姑娘 (gūniang)). source: https://en.wiktionary.org/wiki/小姐