Smoking in bed on a ship is prohibited（）.

单项选择题Should the vessel have no deratisation certificate at the time of her delivery，she（）be held to be unseaworthy.

A.shall
B.should
C.may
D.would

单项选择题Proper use shall be made（）radar equipment if fitted and operational.

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

单项选择题Keep clear（）the buoy.

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

单项选择题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

单项选择题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