單項選擇題The main function of piston compression rings is to （）

A.prevent excessive cylinder liner wear
B.reduce friction losses in the engine
C.seal the space between the piston and the liner
D.limit upward flow of lube oil into the combustion space


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1.單項選擇題Modern marine diesel engines using mechanical fuel injection, operate on a combustion cycle which is（）

A.a combination of constant volume and constant pressure
B.a combination of constant temperature and constant pressure
C.entirely constant pressure
D.entirely constant volume

2.單項選擇題The function of the piston compression rings used in a diesel engine is to （）

A.seal the space between the piston and liner
B.transmit heat from the piston to the cylinder liner
C.reduce the amount of combustion gas blow-by
D.all of the above

3.單項選擇題What determines the number of events occurring in a cycle of operation in an internal combustion engine?（）

A.Crankshaft revolution
B.Type of engine (diesel or gasoline)
C.Distance a piston travels during a stroke
D.Number of pistons

4.單項選擇題Which of the factors listed has the greatest effect on the mechanical efficiency of a diesel engine?（）

A.temperature of the intake air
B.friction within the engine
C.mechanical condition of the supercharger
D.mechanical condition of the turbocharger

5.單項選擇題A practical way of checking for excessive fuel injection in one cylinder of an operating diesel engine is to （）

A.feel the high pressure fuel line
B.check the cylinder exhausts for white smoke frequently
C.check the cylinder exhaust temperature
D.isolate each cylinder and inspect the injector