“炉火纯青”用英语怎么说

炉火纯青:
reach a high degree of technical or professional proficiency

Examples:
1. 他们赞佩表演炉火纯青.
They were impressed by the sheer professionalism of the performance.
2. 她的歌唱得已是炉火纯青.
Her singing was perfection.
3. 他的作品已达到炉火纯青的地步。
His work have reach a high degree of excellence.

炉火纯青
high degree of professional proficiency

High degree of proficience