单项选择题
As an extinguishing agent，foam（）.
A.conducts electricity B.should be directed at the base of the fire C.is most effective on burning gases which are flowing D.extinguishes by cooling oil fires below ignition temperature
单项选择题 Any ship damaging a pipe could（）an immediate danger of fire.
单项选择题 Any firefighting equipment that is carried in addition to the minimum required must（）.
单项选择题 Any extinguishing agent used on a Class C fire must have which important property?（）
