單項選擇題While inspecting the main bearings on a diesel engine you find impregnated dirt and scratches in the bearing surface you would, therefore, suspect that （）

A.the bearing had been overheated
B.water was present in the oil
C.the lube oil was not being properly filtered
D.the maximum allowable bearing pressure had been exceeded


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1.單項選擇題Most large, low-speed, main propulsion diesel engines use duplex lube oil strainer to （）

A.decrease the time required between cleanings
B.removes all large and small foreign objects
C.ensure a positive flow of oil at all times
D.ensure that all lube oil has been treated twice

2.單項選擇題If the cooling water temperature and the lube oil temperature in a diesel engine are too high, the cause can be （）

A.a dirty lube oil strainer
B.internal water leaks
C.an oil suction line restriction
D.excessive wears of the cooling water pump

3.單項選擇題The reversing cams of some four-stroke/cycle diesel engines are brought into position by （）

A.sliding the camshaft along its axis
B.rotating the cam 180
C.rotating the cam followers 180
D.moving the idler sprockets in the drive chain

4.單項選擇題A diesel engine is equipped with an isochronous hydraulic governorA decrease in load will cause the engine speed to （）

A.decrease only
B.increase only
C.decrease slightly then returned to original speed
D.increase slightly then returned to original speed

5.單項選擇題The arrangement and shape of the cams on a diesel engine camshaft directly control which of the listed groups of operating conditions?（）

A.speed, torque, and horsepower production
B.firing order, valve timing, and valve lift
C.fuel consumption, efficiency, and cylinder pressure
D.scavenge pressure, compression ratio, and exhaust pressure