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单选题
Which of the conditions listed represents the greatest effect of excess frost accumulation on the evaporator coils?（）
A
Keeps the refrigerated space cooler
B
Reduces the efficiency of the plant
C
Takes the load off the compressor
D
Has no affect on the system
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单选题Which of the conditions listed will cause a refrigeration compressor to run constantly without simultaneously decreasing the temperature in the refrigerated space?（）A
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Moisture or foreign matter collecting at the valve seat and orificeC
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单选题For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes?（）A
Chilled water system supply temperatureB
Chilled water system return temperatureC
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Water level in the expansion tank
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High vanadium content fuelD
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单选题The temperature differential occurring between the inlet temperature of the fluid to be cooled and the outlet temperature of the cooling medium in a shell-and-tube heat exchanger is greatest in which of the flow designs listed?（）A
CrossB
ParallelC
CounterD
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Fuel/Air ratioC
Compression pressureD
Lube oil pressure
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单选题Which of the actions listed and instituted on your part will have the greatest lasting effect on the crew with respect to safety?（）A
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单选题Which of the following gases represents the greatest threat to personnel safety in an engine room where the exhaust is leaking from a diesel engine?（）A
Carbon dioxideB
Carbon monoxideC
Carbon trioxideD
Hydrogen sulfide
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The temperature of the air entering the compressorC
The designed rotating speed of the compressorD
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Non-harmonic speedB
Critical speedC
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High fuel consumption and high exhaust temperaturesD
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单选题The arrangement and shape of the cams on a diesel engine camshaft directly control which of the listed groups of operating conditions?（）A
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Only with the masters permissionC
After a 10 minute delay to the input commandD
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单选题0f all the extinguishing agents listed below, which one has the greatest capacity for heat adsorption?（）.A
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Dry chemicalD
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单选题When one cylinder has a lower compression pressure and higher exhaust gas temperature than any of the other engine cylinders, which of the conditions listed will indicated?（）A
Advanced ignitionB
Clogged air intakeC
Leaky exhaust valveD
High exhaust pressure
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单选题Which of the factors listed has the greatest effect on the mechanical efficiency of a diesel engine?（）A
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friction within the engineC
mechanical condition of the superchargerD
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