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单选题
A diesel engine should not be operated at low loads for long periods of time because（）
A
heavy carbon deposits will buildup on the valves and in the exhaust
B
fuel dilution is increased at low load
C
exhaust valves may be damaged
D
all of the above
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electricB
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runs out of fuelB
has low lubricating oil pressureC
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单选题The diesel engine exhaust gas bypass, as fitted with some waste heat boilers, is installed to （）A
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单选题Starting a large low-speed propulsion diesel engine on diesel fuel during cold weather conditions, will be made easier by （）A
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fuel must be preheatedB
intake air should be preheatedC
lube oil outlet temperature should be increased 20℃ above normalD
none of the above
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单选题Which of the listed diesel engine operating conditions should be checked immediately after any diesel engine is started?（）A
Exhaust temperatureB
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a worn cylinderB
broken piston ringsC
any of A and BD
none of the above
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low exhaust valve liftC
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单选题Burning fuel with a high sulfur content in a diesel engine will （）A
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单选题What harmful condition can result if a diesel engine is operated at very light loads for long periods of time?（）A
increased carbon buildupB
burning of intake valvesC
excessive firing pressuresD
increased fuel consumption
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shutting off the fuel supplyC
increasing the engine back pressureD
over-speeding the engine
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air intake is restrictedB
engine is cranked too fastC
vibration dampener is faultyD
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overheated pistons and cylindersD
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考题
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考题
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compression must be low for effective spark ignitionB
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单选题Which is false about engine trials?（）A
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考题
单选题When running a large, low-speed, main propulsion diesel engine on heavy fuel, which of the following precautions should be observed when switching back over to diesel oil?（）A
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increasing the efficiency of propellerD
increasing fuel injection
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high lube oil temperatureB
low lube oil temperatureC
excessive cylinder coolingD
high air injection pressure
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单选题Which of the following conditions may need to be reduced when operating a large, low speed, main propulsion, diesel engine at low loads?（）A
Injection pressuresB
Control air supply pressureC
Cooling water flow through after-coolersD
Lube oil temperature
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