A cutoff valve in the fire-main system of a ship may be closed to protect the portion of the system on an exposed deck from（）.

单项选择题A combustible gas indicator meter is calibrated to read the percentage of（）.

A.vapor to oxygen
B.the flammable limit concentration
C.the autoignition concentration
D.the lower explosive limit concentration

单项选择题A class C fire would be burning（）.

A.fuel oil
B.wood
C.celluloid
D.electrical insulation

单项选择题A class B fire is most successfully fought by（）.

A.preventing oxygen from reaching the burning material
B.cooling the burning material below its ignition temperature
C.using the extinguishing agent to make the burning material fire-resistant
D.using the extinguishing agent to absorb the heat

单项选择题A Certificate of Inspection issued to a small passenger vessel describes（）.

A.the mimimum fire extinguishing equipment，lifejackets，survival and rescue craft she must carry
B.the name of the managing operator
C.any special conditions or restrictions on her operation
D.All the above

单项选择题A carburetor is required to have a safety device called a(n)（）.

A.pressure release
B.backfire flame arrestor
C.automatic shut off
D.flow valve