When water is used to fight a fire on board a ship，the effect of the weight of the water must be taken into account. How much sea water will increase the weight displacement by one ton?（）

单项选择题When using carbon dioxide to fight a fire on a bulkhead，the CO2 should be applied（）.

A.first to the bottom of the flaming area，sweeping from side to side，and following the flames upward
B.in a circular motion from the middle of the bulkhead outward
C.to the top of the flaming area，sweeping from side to side，and working toward the bottom
D.in an up-and-down motion from one side of the bulkhead to the other

单项选择题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

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