单项选择题
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
