单项选择题
In the GMDSS, distress alerting can be transmitted in（）directions.
A.1 B.2 C.3 D.4
单项选择题 We（）the distress signal on our own radio before the shore station relayed it to us.
单项选择题 The frequency 156.525MHZ and 156.8MHZ should be used in the band of（）.
单项选择题 Actually, the date for entry into effect will be 1st February（）.Though the text does not tell us about it.
