An ABC dry chemical fire extinguisher would be LEAST effective against a fire in（）.

单项选择题All portable fire extinguishers must be capable of being（）.

A.carried by hand to a fire
B.carried or rolled to a fire
C.recharged in the field
D.used on class 'B' fires

单项选择题All of the following are part of the fire triangle EXCEPT（）.

A.electricity
B.fuel
C.oxygen
D.heat

单项选择题After extinguishing a paint locker fire using the fixed CO2 system，the next action is to have the space（）.

A.opened and burned material removed
B.left closed with vents off until all boundaries are cool
C.checked for oxygen content
D.doused with water to prevent reflash

单项选择题After extinguishing a fire with CO2，it is advisable to（）.

A.use all CO₂ available to cool the surrounding area
B.stand by with water or other agents
C.thoroughly ventilate the space of CO₂
D.jettison all burning materials

单项选择题According to the regulations，what fire safety control feature is required in quick-closing shut off valves?（）

A.Electrical cut off switch
B.A fusible link
C.Manual cut off switch
D.A water spray actuator