单项选择题
When used to fight fire，carbon dioxide（）.
A.is effective if used promptly on an oil fire B.has a greater cooling effect than water C.is lighter than air D.is harmless to cargo and crew
单项选择题 When two fire hose teams are attacking a fire they should（）.
单项选择题 When towing astern what equipment should be stowed ready for use near the towline?（）
单项选择题 When should a fire be ventilated?（）
