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（）.
单项选择题 After extinguishing a fire with CO2，it is advisable to（）.
单项选择题 According to the regulations，what fire safety control feature is required in quick-closing shut off valves?（）
