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單項(xiàng)選擇題

A (n) （） is a chemical or electro-chemical attack on the metal surface which may be further increased if the sea-water is polluted.

A.erosion
B.corrosion
C.cavity
D.scouring

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單項(xiàng)選擇題

A propeller of 5~65m in diameter, having a mean pitch of 4~88m, turning at 72 rpm, at a speed of 11 knots (339~79m/min), will give （） of apparent slip.

A.0~967
B.0~033
C.0~031
D.0~969

單項(xiàng)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

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