单项选择题
A.4 B.9 C.8 D.5
why should the SES operators be very careful when the s...
单项选择题why should the SES operators be very careful when the ship enters the area where three ocean regions overlap? Because（）.
A.the weather over there is always terrible B.the condition there is complicated C.the signals are too strong D.their SES may receive the signals from unwanted satellite
The quality of EGC messages is（）affected by the positio...
单项选择题The quality of EGC messages is（）affected by the position of the ship, the time of reception and climatic conditions.
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
