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（）.
A.30 gallons per minute B.40 gallons per minute C.50 gallons per minute D.60 gallons per minute
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（）.
单项选择题 A passenger vessel is required to have a supervised patrol when（）.
