单项选择题

A propeller, in order to operate efficiently, must rotate at a relatively （） speed.

A.high
B.low
C.fast
D.lowly

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单项选择题

Why a gearbox is needed in a ship driven by a medium-speed diesel engine?（）

A.To reduce the main engine speed
B.To increase the main engine speed
C.To govern the main engine speed
D.To fix the propeller shaft

单项选择题

Which one is not true?（）

A.Two main areas of skill are involved in the construction of ship
B.There are distinct divisions in responsibilities between naval architects and marine engineers
C.Each ship will assume varying proportions according to its type
D.Ships can be divided into different categories from different perspectives

单项选择题

The displacement of a ship is to the total weight, all told, of the relevant loaded ship（）

A.larger
B.equal
C.smaller
D.equivalent