单项选择题

When using a high-velocity fog stream in a passageway，t……

When using a high-velocity fog stream in a passageway，the possibility of a blow back must be guarded against. Blow back is most likely to occur when（）.

A.pressure builds up in the nozzle which causes a surge of water
B.the only opening in a passageway is the one from which the nozzle is being advanced
C.pressure in the fire hose drops below 100 psi
D.a bulkhead collapses due to heat and pressure

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热门试题

单项选择题When used to fight fire，carbon dioxide（）.

A.is effective if used promptly on an oil fire
B.has a greater cooling effect than water
C.is lighter than air
D.is harmless to cargo and crew

单项选择题When two fire hose teams are attacking a fire they should（）.

A.use different fire hose pressures
B.use fire hoses of different sizes
C.not attack the fire from opposite sides
D.not wear protective clothing

单项选择题When towing astern what equipment should be stowed ready for use near the towline?（）

A.First aid kit
B.Axe or cutting torch
C.Fire extinguisher
D.Chafing gear

单项选择题When should a fire be ventilated?（）

A.When attacking the fire directly
B.When using a steam smothering system
C.When using the fixed CO₂ system
D.All of the above

单项选择题When possible，what should be the FIRST step in combating a fire on deck resulting from a cargo overflow or a leaking cargo line?（）

A.Blanket the cargo spill with foam
B.Prevent the spread of fire with a foam dam
C.Apply CO₂ on burning fuel at its source
D.Shut off the transfer of cargo