单项选择题
The transmission of messages respecting the dangers specified is free（）cost to the ships concerned.
A.of
B.on
C.at
D.in
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相关考题
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单项选择题
The towing light is a(n)（）.
A.flashing amber light
B.yellow light with the same characteristics as the sternlight
C.all-round yellow light
D.yellow light with the same characteristics as the masthead light -
单项选择题
The term OIL as used in the Oil Pollution Regulations means（）.
A.fuel oil
B.sludge
C.oil refuse
D.All of the above -
单项选择题
The radiotelephone safety message urgently concerned with safety of a person would be prefixed by the word（）.
A.Mayday
B.Pan
C.Safety
D.Interco
