單項選擇題A diesel engine experiences a sudden loss in speed, accompanied by black exhaust smoke, with the fuel rack at maximum, and speed remaining below normal the probable（）

A.engine overload
B.leaky valves
C.stuck or broken piston rings
D.low air injection pressure


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1.單項選擇題Which of the following problems can occur if you continually fail to drain off condensate from a starting air receiver?（）

A.Corrosion and eventual failure of the tank
B.Gumming of the tank relief valves
C.Immediate failure of components downstream of the compressed air system
D.Boiling of the water oil mixture as pressure is reduced

2.單項選擇題During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure （）

A.effective cylinder scavenging and cooling
B.constant pressure from the turbochargers
C.cooler operation of the exhaust system
D.effective constant pressure for turbocharger operation

4.單項選擇題When the normal compression ratio of a diesel engine is not very high, misfiring at light loads may be caused by （）

A.overloading the engine
B.low exhaust valve lift
C.excessive cylinder cooling
D.insufficient mechanical clearance

5.單項選擇題In a two-stroke/cycle diesel engine, the exhaust gases are expelled from the cylinder by the（）

A.exhaust manifold
B.valve bridge
C.pressure of the fresh air charge
D.valve adjusting gear