词汇与结构An aircraft planning to cruise at 40,000 ft (12,000 m) is programmed to rise gradually from take-off to around 8,000 ft (2,400 m) in cabin pressure altitude, and to then reduce gently to ______ the ambient air pressure of the destination.
A. remain
B. match
C. keep
D. stay
词汇与结构Pressurization of aircraft cabins above 3,000 meters (9,800 ft) generally avoids significant hypoxia, altitude sickness, _________ and barotrauma.
A. decompression sickness
B. compression sickness
C. decompression illness
D. compression illness
词汇与结构An oxygen system is ________ but only for emergency use and only intended to allow time to descend to a safe altitude.
A. restrained
B. retained
C. reserved
D. restricted
词汇与结构Cabin altitude is not normally______ at ground level (0ft) pressure throughout the flight because doing so stresses the fuselage and uses more fuel.
A. maintained
B. declared
C. claimed
D. remained