單項選擇題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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1.單項選擇題Diesel engine fuel oil contamination often results in （）

A.governor malfunctions
B.fuel injection system malfunctions
C.high cylinder lube oil temperatures
D.low intake temperatures

2.單項選擇題When a diesel engine is operate at partial load, as compared to full load ,a decrease will occur in the average （）

A.air quantity aspirated
B.fuel injection pressure
C.combustion pressure on the power stroke
D.compression on the compression stroke

3.單項選擇題The most common diesel engine fuel system problems are caused by （）.

A.incorrect adjustments
B.dirty fuel
C.broken fuel lines
D.excessive vibration

4.單項選擇題The power developed by a large slow-speed main propulsion diesel engine is dependent upon the （）

A.quantity of air it takes in and retains in the cylinders during a given time period
B.proportion of trapped air that is utilized in the combustion process
C.thermodynamic efficiency of the engine cycle
D.all of the above

5.單項選擇題Dirt in a fuel oil system of a diesel engine can cause （）

A.damage to strainers
B.over-speeding of the engine
C.excessive cooling of the engine
D.injector damage