單項選擇題

Keep clear（）the buoy.

A.to
B.on
C.of
D.for

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單項選擇題

In the International Code of signals，a group of three letters indicates（）.

A.urgency or an emergency
B.the vessel's national identity signal
C.a group from the general signal code
D.a group from the medical signal code

單項選擇題

In order to prevent galvanic corrosion，an aluminum boat must be insulated from the davits and gripes. Which of the following is acceptable as an insulator?（）

A.Hard rubber
B.Canvas
C.Leather
D.Sponge rubber