oxygen mask

名词 oxygen mask:

1. a breathing device that is placed over the mouth and nose; supplies oxygen from an attached storage tank

1. If air is needed, the oxygen mask in the plane will pop down by itself.
   如果空气缺乏，飞机内的氧气面罩会自动放下。
2. An oxygen mask will come down from overhead in case of an emergency.
   若发生紧急情况，头顶上会降下一只氧气面罩。