消防员在进入浓烟弥漫的建筑前戴上了防护面具。

The firefighters put on their ___masks before entering the smoke-filled building.

外科医生在手术期间佩戴外科口罩是标准流程。

It's standard procedure for the surgeon to wear a surgical ___mask during the operation.

她戴着一个精美的威尼斯面具去参加化装舞会。

She wore a beautiful Venetian ___mask to the costume party.