2 sentences

1. 他是鉴定古董的行家。

   tā shì jiàn​dìng gǔ​dǒng de háng​jiā.

   He is an expert in authenticating antiques.

   Source: Dong Chinese Dictionary

2. 这件古玩的真伪，请行家一鉴便知。

   zhè jiàn gǔ​wán de zhēn​wěi, qǐng háng​jiā yī jiàn biàn zhī.

   An expert can tell the authenticity of this antique at a glance.

   Source: Dong Chinese Dictionary