The passenger oxygen system is a chemically-generated oxygen system for use by passengers and cabin attendants. "the chemically-generated oxygen"means "化学(方法)产生的氧气".
A.1;正确答案A
The passenger oxygen system is a chemically-generated oxygen system for use by passengers and cabin attendants. "the chemically-generated oxygen"means "化学(方法)产生的氧气".
A.1;正确答案A