单项选择题
An emergence sea anchor may be constructed by type of extinguisher?（）.
A.a boat bucket B.an air tank filled with water C.an oar and canvas weighted down D.All of the above
单项选择题 An engine compartment gasoline fire requires which type of extinguisher?（）.
单项选择题 An example of a messenger is a（）.
单项选择题 An inflatable life raft can be launched by（）.
