单项选择题 （）all ships in a large sea area being alerted, an “area call” will normally be transmitted so that only those ships in the vicinity of the distress incident are alerted.

单项选择题 The concept of NAVTEX is of a（）system for the broadcast and reception of MSI.

单项选择题 If no distress acknowledgement is received（）a DSC distress call transmission, then the ship in distress may repeat the DSC distress call attempt after a delay of between 3.5 and 4.5 minutes from the beginning of the initial call.