97免费在线观看视频,亚洲综合自拍网,黄色毛片免费观看,热久久综合网,免费看日产一区二区三区 狠狠操av,久久久涩涩涩,在线精品免费视频,人人插天天干,久久91精品国产91久久

單項選擇題

What is meant by the term “radio silence”?()

A.Stations not directly involved with the on-going distress communications may not transmit on the distress frequency or channel
B.Stations remaining off the air to safeguard proprietary information
C.Two three-minute silent periods,at 15 and 45 minutes after the hour,that provide a transmitting "window" for distressed vessels to transmit distress alerts using J3E
D.Communications on a distress frequency or channel is banned for 24 hours following the cessation of the distress traffic

微信掃碼免費搜題