A.the paint lockerB.spaces open to the atmosphereC.carg……

单项选择题Firefighting foam is only effective when the foam（）.

A.penetrates to the bottom of the fire
B.is kept saturated with low-velocity water fog
C.mixes with the burning fuel oil
D.completely covers the top of the burning liquid

单项选择题Fire may be spread by which means?（）.

A.Conduction of heat to adjacent surfaces
B.Direct radiation
C.Convection
D.All of the above

单项选择题Fire in an engine compartment is best extinguished with carbon dioxide gas (CO2) and by（）.

A.closing the compartment except for the ventilators
B.completely closing the compartment
C.leaving the compartment open to the air
D.increasing the air flow to the compartment by blowers

单项选择题Fire hose should be washed with（）.

A.salt water and a wire brush
B.caustic soap
C.mild soap and fresh water
D.a holystone

单项选择题Fire hose couplings（）.

A.are made of bronze，brass，or soft alloy metals
B.should be painted red in order to identify hose lengths
C.are specially hardened to prevent crushing
D.should be greased frequently