单项选择题
A.a gas mask certified by the Mine Safety and Health Administration
B.the same self-contained breathing apparatus required with the fireman's outfit
C.an oxygen breathing apparatus，provided that the device has been inspected within three years
D.a portable ventilation system that will provide a complete change of air every three minutes
单项选择题 A ship helicopter landing deck on which fueling operations are conducted must have a fire protection system that is capable of discharging at 100 psi pressure a foam spray of at least（）.
单项选择题 A portable foam (stored-pressure type) fire extinguisher would be most useful in combating a fire in（）.
单项选择题 A portable dry chemical fire extinguisher discharges by（）.