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【简答题】
在声场内的一定点位上，将某一段时间内连续暴露不同A声级变化，用能量平均的方法以A声级表示该段时间内的噪声大小，这个声级称为（ ）。
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皮皮学刷刷变学霸
举一反三
【单选题】For diesel engine piston cooling, lubricating oil can be supplied to the pistons by a/an _____.
A.
oil spray
B.
oil bath
C.
oil control rings
D.
drilled passage through the camshaft
【单选题】The oil lubricating diesel engine cylinders usually contain additives formulated to impart a high degree of alkalinity to _____ the acid conditions.
A.
invade
B.
provide
C.
detergent
D.
neutralize
【单选题】Lubricating oil for an engine is stored at the bottom of the _____, known as the sump or in a drain tank located beneath the engine.
A.
sea cheat
B.
air receiver
C.
crankcase
D.
water box
【单选题】Excessive lubricating oil consumption in a running diesel engine can be caused by ________.
A.
clogged lube oil piping
B.
excessive valve-guide clearance
C.
high lube oil viscosity
D.
low lube oil temperature
【单选题】Loss of lubricating oil pressure to the main propulsion diesel engine will actuate a/an _____.
A.
over-speed trip
B.
audible/visual alarm
C.
the ships/boats general alarm
D.
reserve oil storage tank
【简答题】What's the function of the lubricating oil in main engine?
【单选题】In a normally operating diesel engine, the main cause of lubricating oil contamination in the crankcase is a result of the _____.
A.
metal particles loosened by wear
B.
air when no air cleaners are used
C.
condensation of water vapors
D.
breakdown of the lubricating oil by dilution
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