單項選擇題In a four stroke engine, which process lasts the longest period?（）

A.exhaust and suction process
B.suction and compression process
C.combustion and exhaust process
D.working and exhaust process


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1.單項選擇題In the two stroke diesel engine, it is designed so that the oil impingement is timed to proceed only on the piston ring belt during（）

A.compression stroke
B.suction stroke
C.expansion stroke
D.exhaust stroke

2.單項選擇題One advantage of a flash distilling plant when compared to a submerged tube distiller is（）

A.greater distillate purity through high temperature evaporation
B.cold shocking for scale removal is not required
C.less internal corrosion because of lower brine density
D.less feed-water is required for equal plant capacity

3.單項選擇題Sludge may be formed in the oil in the crankcase of a reciprocating air conditioning compressor as a result of （）

A.refrigerant bubbles in the lube oil
B.refrigerant reducing the lube oil viscosity
C.oxidation of the lube oil from overheating
D.reducing the floc or cloud point of the oil

4.單項選擇題Which of the processes listed would be the most satisfactory method to use to lower the humidity of the air being circulated by an air conditioning system?（）

A.Cooling the air to a temperature just above dew point
B.Heating the air to a point at which moisture will boil off ,then re-cooling it
C.Cooling the air to a point below dew point, then reheating it
D.Heating the air and then cooling it to a point below dew point

5.單項選擇題In an air conditioning system, low head pressure associated with a reciprocating compressor can be the result of （）

A.broken valve springs
B.tight drive belts
C.high line voltage
D.air in the system