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單項選擇題In moving forward, a ship imparts forward motion to the water at the stems, this is known as （）.

A.the speed of the vessel
B.the speed of the propeller
C.the wake
D.the wake fraction

1.單項選擇題Wake varies considerably with the form of the vessel, but, generally speaking, the bluffer the ship （） the wake value.

A.the higher
B.the lower
C.the faster
D.the slower

2.單項選擇題When viewed from astern, if the propeller revolves in a clockwise direction when going ahead, it is known as （）.

A.ahead direction
B.astern direction
C.right-handed
D.left-handed

3.單項選擇題The pitch ratio of a propeller is the mean pitch divided by （）.

A.the propeller diameter
B.the propeller radius
C.the pitch angle
D.the length of helix

4.單項選擇題If a line at right angles to the axis rotates about that axis and, at the same time, moves parallel to the axis, it will generate （）.

A.a helix
B.a helicoidal
C.a curve
D.a cone

5.單項選擇題When a point rotates about an axis and, at the same time, moves parallel to that axis, it describes （）.

A.a line
B.a circle
C.a helix
D.an epllicate