单项选择题
Which signal is recognized as a distress signal?（）
A.Directing the beam of a searchlight at another vessel B.A smoke signal giving off orange colored smoke C.A whistle signal of one prolonged and three short blasts D.International Code Signal "PAN" spoken over the radiotelephone
单项选择题 Which signal is detected as originating from a SART?（）
单项选择题 Which of the following statements about transmitting distress messages by radiotelephone is INCORRECT?（）
