In a four stroke engine, which process lasts the longest period?（）

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• In the four-stroke engine, it takes （） to make one power stroke.

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• The exhaust valve opens before bottom dead center in a four stroke engine to（） Ⅰ.allow for blow down Ⅱ.Reduce pumping losses

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• In a closed cooling system for a turbocharged, four-stroke/cycle diesel engine, fluctuating water pressure can be caused by （）

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• In a four-stroke/cycle diesel engine, after the completion of the power stroke, the piston will move（）

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• Which of the following conditions can cause above normal air temperature to develop in the intake manifold of a four-stroke/cycle turbo-charged diesel engine?（）

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• In a four-stroke engines the camshaft rotates at （）.

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• In a four-stroke/cycle diesel engine, the camshaft rotates at （）

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• Proper lubrication of the main bearings is more easily obtained in a single acting, four-stroke/cycle diesel engine than in a tow-stroke/cycle diesel engine because（）.

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• In an ordinary four-stroke engine the exhaust valves open （）

  A . after TDC B . before TDC C . after BDC D . before BDC

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• What is the speed of the crankshaft in a four-stroke/cycle engine when the camshaft is turning at 750 rpm?（）

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• In four-stroke diesel engine, the cycle of events is completed in （) of crankshaft.A.one

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• The exhaust valve opens before bottom dead center in a four stroke engine to______Iallow for blow down IIReduce pumping losses

  A.I only B.II only C.both I and II D.neither I nor II

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• Among the four strokes of a four-stroke diesel engine,suction and expansion strokes are the upward strokes.()

  此题为判断题(对，错)。

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