Most air conditioning units have （） for adjusting the ratio of recirculated fresh airCare must be taken not to reduce the fresh air so that stuffiness or smells arise.

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• The humidifier’s valve of air-condition should be （）, when the temperature is lower than 0℃.

  A . A.decreased B . B.increased C . C.fixed D . D.closed

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• Routine maintenance on a Central Control Room hermetically sealed air conditioning unit should include （）

  A . changing the air filter B . recharging the system C . changing compressor lubricant D . renewing container vacuum

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• The purging of air from an elector-hydraulic steering gear unit is necessary when（）

  A . changing over to hand pump operation B . engaging the trick wheel C . the system has been filled with new oil D . the rudder angle indicator does not match the helm positio

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• Sludge may form in the crankcase of an air conditioning compressor as a result of （）.

  A . bubbling refrigerant B . overheating and oxidation C . lowered operating temperatures D . reducing the cloud or flash point

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• 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

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• When under maneouvring conditions with the machinery being manually operated the control unit or console should be （）

  A . automatically controlled B . continuously manned C . off power D . none of the above is true

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• In extreme weather conditions, either hot or cold, control of the air conditioning plant presents （） difficulties.

  A . few B . little C . a little D . le

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• Sludge may form in the lubricating oil crankcase of a reciprocating air conditioning compressor as a result of （）.

  A . wax precipitation in the lube oil B . contamination by dust, scale, or moisture C . refrigerant bubbles in the lube oil D . refrigerant reducing the lube oil viscosity

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• Increasing the moisture content of conditioned air is known as （）.

  A . moisturizing B . dehumidification C . dampening D . humidificatio

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• The quantity of cooled air delivered by an air conditioning unit should （） the sum of the quantity of air re-circulated to the unit and the quantity mechanically exhausted.

  A . balance B . not balance C . be more than D . be less tha

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• Under normal conditions, the quantity of air circulation becomes less and less.What is the reason?（）

  A . dirty delivery ducts B . too much refrigerant C . the fouling filters D . high temperature outside

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• If plastic film insulation becomes damaged in air conditioning system, （） may form within the film.

  A . evaporation B . condensation C . liquefies D . vaporizatio

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• For the proper control of the air temperature in an air conditioning system using chilled water circulation, which of the listed conditions should remain constant regardless of load changes?（）

  A . Chilled water system supply temperature B . Chilled water system return temperature C . Compressor discharge temperature D . Compressor suction pressure

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• （） is used for sensing the temperature of the room in the air condition system.

  A . An expansion valve B . An evaporator C . A thermostat D . A condenser

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• In an air conditioning system, moisture is removed from the air by（）

  A . filers B . separators C . ducted traps D . dehumidifier

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• In a chilled water air conditioning unit using a reciprocating compressor, the refrigerating effect of the primary refrigerant can be increased by （）.

  A . increasing refrigerant pressure in the coil B . increasing chilled water flow through the cooler C . sub-cooling the refrigerant in the condenser D . superheating the refrigerant in the compressor

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• In reference to air conditioning, when air attains the maximum amount of moisture it can hold at a specific temperature, it is said to be （）.

  A . superheated B . saturated C . condensed D . convected

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• We don’t need air conditioning, ____?

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• Heating and air conditioning are examplesof common costs of all departments in a retail store.

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• It can be inferred from the passage that most people in the United States in 1955 viewed the national economy with an air of _________.

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• Can you ________ the air conditioning?

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• The only air-conditioning on the boat was ______.

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• What was the problem with the air conditioning Mr. Henry purchased？

  A．The air conditioning filter wasn"t replaced. B．The thermostat was turned down too low. C．The freon pressure was lower than normal. D．The fan motor was out of order.

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• SI: What’s wrong with the air conditioning system S2: It doesn’t work well. Q: What’s wrong with the air conditioning system 02020357

  A．The air conditioning system is in good order． B．There is something wrong with it． C．The air conditioning system is out of stock． D．The air conditioning system runs well．

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