单项选择题
How does foam extinguish an oil fire?（）.
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
单项选择题 How do you operate a portable CO2 fire extinguisher?（）.
单项选择题 High-velocity fog（）.
单项选择题 Halon from extinguishers used on a class B fire，should be directed（）.
