单项选择题
A.solid materials such as wood or bales of fiber B.inflammable liquids C.electrical equipment D.metallic solids
Foam is a very effective smothering agent and（）.A.it pr...
单项选择题Foam is a very effective smothering agent and（）.
A.it provides cooling as a secondary effect B.works well on extinguishing electrical fires C.can be used to combat combustible metal fires D.All of the above
Foam extinguishes a fire mainly by（）.A.coolingB.chemica...
单项选择题Foam extinguishes a fire mainly by（）.
A.cooling B.chemical action C.smothering D.inerting the air
Foam extinguishes a fire by（）.A.smothering the burning ...
单项选择题Foam extinguishes a fire by（）.
A.smothering the burning material B.chemical combination with burning material C.absorbing the burning material D.organic destruction of the burning material
