The canvas covering of fire hose is called the（）.

A.refractory
B.the screen wall
C.the water wall
D.fire plate

A.the accumulation of explosive gases
B.faster cooling of the fire
C.the fire to spread through the ventilation system
D.fixed foam systems to be ineffective

A.must be fixed if the vessel exceeds 12 meters in length
B.may be used as a fire pump
C.must be portable if there are more than 4 watertight compartments
D.must be capable of pumping at least 450 gpm