单项选择题
A.cooling the gas below the ignition point B.cutting off the supply of oxygen C.stopping the flow of gas D.interrupting the chain reaction
A chemical additive to LPG gives it a characteristic（）....
单项选择题A chemical additive to LPG gives it a characteristic（）.
A.odor B.color C.pressure D.density
On a hydrocarbon flammability chart the line which exte...
单项选择题On a hydrocarbon flammability chart the line which extends from 0% to 21.8% oxygen，lying tangent to the flammability range，is called the（）.
A.mimimum oxygen content line B.critical displacement line C.critical dilution line D.upper threshold limit
