单项选择题
A.International Code Signal AA B.orange-colored smoke C.red flares D.the repeated raising and lowering of outstretched arms
All of the following are distress signals EXCEPT（）.A.th...
单项选择题All of the following are distress signals EXCEPT（）.
A.the continuous sounding of any fog signal apparatus B.giving five or more short and rapid blasts of the whistle C.firing a gun at intervals of about a minute D.a barrel with burning oil in it，on deck
After putting on a self-contained breathing apparatus，y...
单项选择题After putting on a self-contained breathing apparatus，you open the air supply and hear a continuous ringing of a bell. What does this mean?（）.
A.The unit is working properly B.The face mask is not sealed properly C.The air bottle needs to be refilled D.The air supply hose has a leak
After launching，an inflatable raft should be kept dry i...
单项选择题After launching，an inflatable raft should be kept dry inside by（）.
A.opening the automatic drain plugs B.draining the water pockets C.using the electric bilge pump D.using the bailers and cellulose sponge
