单项选择题
Any extinguishing agent used on a Class C fire must have which important property?（）
A.Cooling ability B.Leaves no residue C.Penetrating power D.Nonconductivity
单项选择题 An inert gas system on a tanker should be used to（）.
单项选择题 An inert gas system is designed to reduce the possibility of tank explosions by（）.
单项选择题 An important step in fighting any electrical fire is to（）.
