单项选择题
A.TTT B.SOS C.The spoken word URGENCY D.The spoken word PAN
Messages concerning weather conditions transmitted by r...
单项选择题Messages concerning weather conditions transmitted by radiotelephone are preceded by（）.
A.MAYDAY B.PAN-PAN C.SECURITE D.SOS
The radiotelephone message that indicates a station is ...
单项选择题The radiotelephone message that indicates a station is about to transmit a message concerning the safety of navigation or important meteorological warnings commences with（）.
A.TTT B.The spoken word PAN C.The spoken word SECURITE D.XXX
The Urgency Signal（）indicates that the station calling ...
单项选择题The Urgency Signal（）indicates that the station calling has a very urgent message to transmit concerning the safety of a ship or aircraft，or of some person on board or within sight.
A.SOS B.XXX C.TTT D.PAN
