单项选择题
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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相关考题
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单项选择题
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 -
单项选择题
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 -
单项选择题
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
