单项选择题
A.specific gravity or relative density
B.open flash point and closed flash point values
C.higher calorific and lower calorific values
D.cloud point and pour point values
单项选择题 （） is the temperature at which a liquid fuel gives off sufficient vapor to form an ignitable mixture near its surface.
单项选择题 A combination combustible gas and oxygen indicator is an instrument that measures the（） of both combustible gas and oxygen; each is indicated on a separate meter.
单项选择题 Deficiencies in the categories of Life-saving, Safety in General, Fire-fighting Appliances and Load Line （） approximately 66% of all deficiencies.