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單項(xiàng)選擇題

A high-velocity fog stream can be used in fire fighting situations to drive heat and smoke ahead of the fire fighters in a passageway. This technique should only be used when().

A.using a 2-1/2 inch hose
B.there is an outlet for the smoke and heat
C.the fire is totally contained by the ship's structure
D.at least two fog streams can be used

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