这是专业人士的鉴定。

Zhè shì zhuānyè rénshì de jiàndìng.

This is the appraisal of a professional.

专家正在进行艺术品的鉴定工作。

Zhuānjiā zhèngzài jìnxíng yìshùpǐn de jiàndìng gōngzuò.

Experts are conducting the appraisal of artworks.

他的签名经过专业人员的鉴定。

Tā de qiānmíng jīngguò zhuānyè rényuán de jiàndìng.

His signature has been authenticated by professionals.