单项选择题
A.SOS three times B.Additional transmissions to aid direction finding C.E for one minute，followed by T for one minute D.Two tones，10-15 seconds each
A message giving warning of a hurricane should have whi...
单项选择题A message giving warning of a hurricane should have which prefix when sent by radiotelephone?（）
A.Pan-Pan (3 times) B.Securite Securite Securite C.TTT TTT TTT D.No special prefix
A Coast Guard radiotelephone message about an aid to na...
单项选择题A Coast Guard radiotelephone message about an aid to navigation that is off station is preceded by the word（）.
A.PAN-PAN B.MAYDAY C.SOS D.SECURITY
A radiotelegraph message commencing with XXX has the sa...
单项选择题A radiotelegraph message commencing with XXX has the same meaning as a message sent by the radiotelephone commencing with（）.
A.TTT B.SOS C.The spoken word URGENCY D.The spoken word PAN
