Foam extinguishes a fire mainly by（）.

A . Dry chemical B . Halon C . Low velocity fog D . Steam

A . a blanket of bubbles formed on the surface of the fire B . smothering C . cooling D . isolating the heat from the fuel

A . mattress fires B . oil fires C . wood fires D . All of the above

A . Nitrogen B . Carbon dioxide C . Sodium D . Oxyge

A . By cooling the oil below the ignition temperature B . By removing the fuel source from the fire C . By excluding the oxygen from the fire D . By increasing the weight of the oil

A . solid materials such as wood or bales of fiber B . flammable liquids C . electrical equipment D . metallic solid

A . generators B . oil drums C . the bridge controls D . combustible metal

A . solid materials such as wood or bales of fiber B . inflammable liquids C . electrical equipment D . metallic solid

A . breaking the chain reaction B . smothering the fire C . cooling the fire D . coating the fuel with a nonflammable surface

A . shutting off the air supply B . cooling the fuel to below ignition temperature C . dispersing the fuel D . removing the source of ignitio

A . soda acid B . foam C . CO D . sand

A . at least annually B . whenever it is below its required weight C . only if the extinguisher has been used D . before every safety inspectio

A . the heat B . the fuel C . the oxygen D . any of the above

A . turning it upside down B . pressing the foam lever C . squeezing the grip handle D . opening the hose valve

A . soild materials such as wood or bales of fiber B . flammable liquids C . a piece of electrical equipment D . combustible metallic solid

A . cooling B . smothering C . chemical action D . All of the above

A . air from contacting the oil vapors B . permitting re-ignition boiling of the heated oil C . spontaneous combustion below the oil surface D . toxic fumes from escaping to the surface

A . generators B . oil drums C . the bridge controls D . combustible metal

A . cooling B . smothering C . chemical action D . All of the above

A . Carbon dioxide B . Water (stored pressure) C . Foam D . Carbon tetrachloride