Keep clear（）the buoy.

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

单项选择题In battery charging rooms，ventilation should be provided（）.

A.at the lowest point
B.near the batteries
C.at the highest point
D.only when charging is in progress

单项选择题If passengers are on board when an abandon ship drill is carried out，they should（）.

A.take part
B.watch
C.go to their quarters
D.stay out of the way and do what they want

单项选择题I would be very much（）if you could arrange for a radio technician to come on board as soon as possible for my radar repair.

A.obliged
B.obliging
C.oblige
D.being obliged