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单选题
Abnormal crankpin bearing and piston skirt surface wear indicate（）
A
a restricted air intake
B
a clogged connecting rod oil passage
C
incorrect connecting rod alignment
D
high cylinder firing temperatures
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corrosion frettingB
insufficient lubricationC
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单选题One method of determining crankshaft misalignment is by（）A
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单选题Which of the following statements concerning cylinder liner wear is true?（）A
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Ⅱ only is correctC
both Ⅰ and Ⅱ are correctD
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单选题Ring groove inserts are occasionally used on aluminum alloy piston to（）A
reduce the ring groove wear rateB
seal against crankcase vaporsC
lessen the wear on aluminum part of the cylinderD
allow for the greater expansion rate of aluminum
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单选题Lubricating oil used in a diesel engine serves to（）A
reduce the wear of bearing surfacesB
cool the bearing surfacesC
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the piston cooling oil return pipesB
the main and crankpin bearingsC
thrust and intermediate bearingsD
stern tube and thrust bearings
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单选题Cold clearances between the skirt of an aluminum piston and the cylinder liner is about （）A
twice as large as with a cast iron pistonB
the same size as with a cast iron pistonC
half as large as with a cast iron pistonD
the same size as the crown of an aluminum piston
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