单项选择题
A yellow signal floating in the air from a small parachute，about 300 feet above the water，would indicate that a submarine（）.
A.has fired a torpedo during a drill
B.is about to rise to periscope depth
C.is on the bottom in distress
D.is disabled and unable to surface
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相关考题
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单项选择题
Which statement is TRUE concerning the danger signal?（）.
A.When any vessel fails to understand the intentions of an approaching vessel she must sound the danger signal
B.Only the stand-on vessel can sound the danger signal
C.Distress signals may be used in place of the danger signal
D.The danger signal consists of 4 or more short blasts of the whistle -
单项选择题
In the safety communication，you can get your R/O（）it for you.
A.do
B.to do
C.doing
D.done
