单项选择题
A.one B.two C.three D.four
The operator of the ship’s radiotelephone，if the radiot...
单项选择题The operator of the ship’s radiotelephone，if the radiotelephone is carried voluntarily，must hold at least a（）.
A.Mate's license B.Restricted radiotelephone operator permit C.Second-class radio operator's license D.Seaman's document
The operation of which aids to navigation may be suspen...
单项选择题The operation of which aids to navigation may be suspended during war or national emergency（）.
A.Navigational satellites B.Loran C.Omega D.Any of the above
The loran lines drawn on navigation charts represent（）....
单项选择题The loran lines drawn on navigation charts represent（）.
A.Ground waves B.Skywaves C.Either ground waves or skywaves interchangeably D.An average between ground wave and skywave positions
