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单选题
Electrical failures in motors are caused by the breakdown of insulation, which may be caused by （）
A
penetration of moisture
B
accumulation of dirt
C
overheating
D
All of the above
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单选题The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the（）.A
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operation of electrical equipment and generators on board shipB
the earth's magnetic field affecting the ship's hard iron during constructionC
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单选题If clearance between a piston and the cylinder wall is excessive, piston slap will occurThe slap itself is caused by （）A
alternation of side thrustB
a breakdown of the lube oil film on the cylinder wallC
worn piston boss piston pin bearingsD
fluctuating gas pressure in the combustion space
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单选题The most common forms of main drive used on deck auxiliaries are （）.A
steam plants, electric motors and compressed airB
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单选题Magnets are placed in horizontal trays in the compass binnacle to compensate for the（）.A
induced magnetism in the vessel's horizontal soft ironB
change in the magnetic field when the vessel inclines from verticalC
permanent magnetism of the vesselD
magnetic fields caused by electrical currents in the vicinity
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问答题什么是 device breakdown voltage？
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