The function of （）is to prevent sailors from overboarding.

单项选择题The （）has four blades.

A.windlass
B.steer
C.propeller
D.helm

单项选择题The main body of a vessel is the （）.

A.hull
B.superstructure
C.engine room
D.poop

单项选择题Sailors should keep （）at sea.

A.lookout
B.outlook
C.uplook
D.lookup

单项选择题（）refers to the height from the waterline to the bottom of the ship.

A.Draft
B.Freeboard
C.Derrick
D.Drift

单项选择题（）refers to the repair the ship every year.

A. Voyage repair
B. Annual repair
C. Periodical repair
D. Survey check