单项选择题
A.sometimes B.all times C.never D.partly
The identification character of each Navtex station is ...
单项选择题The identification character of each Navtex station is regarded as（）to the messages.
A.the only preamble B.a part of the preamble C.the closing D.the suspension
Exchange of answerbacks act s a confirmation that the m...
单项选择题Exchange of answerbacks act s a confirmation that the messages（）at the destination.
A.have received B.have been received C.are received D.are being received
The distance between the two NAVTEX stations with the s...
单项选择题The distance between the two NAVTEX stations with the same B1 character should be not exceed（）nautical miles.
A.400 B.240 C.450 D.180
