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
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相关考题
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单项选择题
Messages concerning weather conditions transmitted by radiotelephone are preceded by（）.
A.MAYDAY
B.PAN-PAN
C.SECURITE
D.SOS -
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 -
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
