单项选择题
Halon extinguishers used on a class C fire should be directed at the（）.
A.base of the equipment B.top of the equipment C.power source D.source of the fire
单项选择题 Good housekeeping on a vessel prevents fires by（）.
单项选择题 Generally，the first action in extinguishing an LFG fire caused by escaping gas is to（）.
单项选择题 Gas masks（）.
