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?（）

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

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

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