单项选择题
A.at the top of the flames B.at the base of the fire near the edge C.in short quick bursts D.toward the upwind side of the fire
Halon fire extinguishers are NOT effective when used on...
单项选择题Halon fire extinguishers are NOT effective when used on which types of fires?（）
A.Fires in electrical equipment B.Flammable oils and greases C.Class A fires in ordinary combustibles D.Materials containing their own oxygen
Halon extinguishes fire primarily by（）.A.coolingB.smoth...
单项选择题Halon extinguishes fire primarily by（）.
A.cooling B.smothering C.shielding of radiant heat D.breaking the chain reaction
Halon extinguishes a fire by（）.A.breaking the chain rea...
单项选择题Halon extinguishes a fire by（）.
A.breaking the chain reaction B.smothering the fire C.cooling the fire D.coating the fuel with a nonflammable surface
