单项选择题
Generally，the first action in extinguishing an LFG fire caused by escaping gas is to（）.
A.sweep flames away with water spray B.shut off the leak C.use a chemical foam fire extinguisher D.call the local fire department
单项选择题 Gas masks（）.
单项选择题 Fusible-link fire dampers are operated by（）.
单项选择题 Foam-type portable fire extinguishers are most useful in combating fires involving（）.
