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單項(xiàng)選擇題

A(n) （） is a mechanical attack on the metal surface which may be due to a disturbance in the flow of the water over the blade of the propeller.

A.erosion
B.corrosion
C.pitting
D.dezincification

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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

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

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