A.blows the fire back toward the vesselB.comes over the……

单项选择题A definite advantage of using water as a fire extinguishing agent is its characteristic of（）.

A.alternate expansion and contraction as water in a liquid state becomes a vapor
B.absorption of smoke and gases as water is converted from a liquid to a vapor
C.rapid contraction as water is converted from a liquid to a vapor
D.rapid expansion as water absorbs heat and changes to steam

单项选择题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（）.

A.damage from crane operations
B.being used for wash down purposes
C.accidental diversion of flow to wrong location
D.freezing

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