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单选题
When it is necessary to open a refrigeration system for repairs and the system will be open for more than a few minutes, the open ends of the system should be （）.
A
dehydrated
B
purged
C
plugged
D
evacuated
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单选题Low compressor head pressure in a refrigeration system can be caused by（）.A
insufficient condenser cooling waterB
excessive condenser cooling waterC
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单选题Purging air from a hydraulic system is necessary when（）A
adding small amounts of oil to the systemB
the system has been overheatedC
the system has been drained and then filled with new oilD
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The open field system provided a good opportunity to experiment.B
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The open field system made livestock farming difficult.
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单选题When liquid reaches the compressor of a refrigeration system through the suction line, the condition is called （）.A
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superheatingC
overflowingD
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单选题In a refrigeration system, the refrigerant absorbs the latent heat of vaporization in the（）.A
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filterB
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单选题Refrigerant is circulated through a refrigeration system by the （）.A
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单选题One cause of high head pressure occurring in a refrigeration system can be （）.A
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a low refrigerant charge in the systemC
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单选题Moisture in a refrigeration system can cause （）.A
freezing the expansion valve closedB
corrosion of system pipingC
improper temperature regulationD
all of the above
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单选题When the refrigeration demand is small,（）A
the expansion valve will move toward the wide open positionB
the expansion valve will move toward the closing positionC
the feeler bulb will conveys the high temperatureD
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考题
单选题While troubleshooting a refrigeration system for low head pressure, liquid refrigerant flooding back from the evaporator is determined to be the causeIt may be necessary to （）.A
change the expansion valve adjustmentB
readjust the water regulating valve to increase the flow of waterC
purge air from the condenserD
clean the waterside of the condenser
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单选题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.A
increase the amount of cooling water to the condenserB
decrease the amount of cooling water to the condenserC
add more refrigerant to the systemD
remove some refrigerant from the system
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单选题In a refrigeration system, if the cooling water to the condenser fails, the（）.A
box temperature solenoid valve will closeB
expansion valve will closeC
compressor will shutdownD
king valve will open
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单选题To correct the condition of slugging and flooding back in a refrigeration system, it may be necessary to （）.A
re-adjust the discharge pressureB
clean the expansion valve screenC
add refrigerantD
adjust the expansion valve
考题
单选题Which of the listed refrigeration system components keeps the refrigerant circulating through the system?（）A
Expansion valveB
CondenserC
EvaporatorD
Compressor
考题
单选题Which of the following statements best describes the relationship between a logical volume and a journaled file system (JFS)?（）A
Increasing the size of a logical volume also increases the size of the file systemB
Reducing the size of a logical volume requires reducing the size of the file system firstC
Increasing the size of a file system requires increasing the size of the logical volume firstD
Increasing the size of a file system also increases the size of the logical volume when necessary
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单选题A pressure drop in the liquid line of a refrigeration system may cause（）A
the solenoid valve to seizeB
the compressor to huntC
flash gas to form in the liquid lineD
the expansion valve to freeze open
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