A chart position enclosed by a square is a(n)（）.

A “Mediterranean moor” should be used when（）.

A “fifteen-pound” CO2 extinguisher is so called because（）.

A crew member has suffered frostbite to the toes of the right foot. Which is NOT an acceptable first aid measure?（）

A backlash below a lock is defined as a（）.

A tonnage tax is levied according to the（）.

A buoy with a composite group-flashing light indicates a(n)（）.

A chart with a natural scale of 1:160，000 is classified as a（）.

A ballasted vessel sinks enroute to a dry dock. Under these circumstances，the vessel’s owner can claim（）.

A chain bridle is preferable to a wire rope towing bridle on a long ocean tow because chain（）.