单项选择题
A.NAVETEX receiver B.Search and Rescue Transponder C.Emergency Position Indicating Radio Beacon D.Digital selective calling
（）is used for calling and replying,and for transmitting...
单项选择题（）is used for calling and replying,and for transmitting acknowleding and relaying distress alerts.
A.NAVETEX receiver B.Search and Rescue Transponder C.Emergency Position Indicating Radio Beacom D.Digital selective calling
（）provides a paper trace of course steered by the vesse...
单项选择题（）provides a paper trace of course steered by the vessel against time.
A.The echo sounder B.The radar C.The course recorder D.The direction finder
（）is a radio receiver with ablity to sense direction of...
单项选择题（）is a radio receiver with ablity to sense direction of the incoming radio waves.
