A.every six months
B.every year
C.every one and half year
D.every two years
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A.foam extinguishers
B.water spray equipment
C.dry powder extinguishers
D.soda-acid extinguishers
A.deprival of oxygen
B.removal of heat
C.spraying of water
D.injecting of soda-acid
A.deprival of oxygen
B.a water spray
C.soda-acid
D.foam
A.combustible material
B.ignition source
C.oxygen
D.A and B and C
A.Two derricks
B.A derrick and a crane
C.Two cranes
D.A crane and a winch
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