單項(xiàng)選擇題The main purpose of the piston oil scraper rings is to （）.

A.seal the space between the piston and the liner
B.reduce the amount of lube oil burned in the combustion chamber
C.transmit heat from the piston to the cylinder liner
D.damp out fluctuations of the piston side thrust


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1.單項(xiàng)選擇題Maximum horsepower of a diesel engine is attained （）.

A.when the engine RPM is pulled down by overload
B.at rated engine RPM
C.at 95 % of rated engine RPM
D.at 95 % of a properly adjusted governor RPM with the engine under full load

2.單項(xiàng)選擇題Engine protection by means of an alarm or shutdown control can be obtained with devices that are sensitive to （）.

A.temperature
B.pressure
C.engine speed
D.all of the above

3.單項(xiàng)選擇題In diesel engines, the four basic events (intake, compression, power and exhaust) are performed once in （）.

A.two crankshaft revolutions in a two-stroke/cycle engine
B.two power strokes in a two-stroke/cycle engine
C.one power stroke in a two-stroke/cycle engine
D.two piston strokes in a two-stroke/cycle engine

4.單項(xiàng)選擇題If the main engine of an unattended engine room shuts down automatically, it will be indicated by an alarm （）.

A.at each control station
B.in the chief engineer’s quarters
C.in the captains quarters
D.All of the above are correct

5.單項(xiàng)選擇題White smoke exhausting from an operating diesel engine may indicate （）.

A.a cracked liner
B.burning lube oil
C.an overloaded engine
D.insufficient combustion air