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
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相关考题
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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 -
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 -
单项选择题
The line connecting the Loran-C master station with a secondary station is called the（）.
A.Focus line
B.Base line
C.Side line
D.Center line
