Which of the following conditions must exist for heat to flow from one object to another、

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• 1A centrifugal pump may fail to deliver water when first started if the ______.

  A.water seal pipe is plugged

  B.pump is not primed

  C.seal ring is improperly located

  D.impeller is flooded

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• 2A pump shaft that is bent or distorted should normally be ______.

  A.repaired by a suitable welding process

  B.straightened by applying heat and torsion

  C.reconditioned by metallizing and machining

  D.replaced with a satisfactory spare

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• 3Which of the valves listed will be cycled from fully open to fully closed when the handle is turned 90 degree、

  A.A rising stem gate valve

  B.A globe stop valve

  C.A check valve

  D.A butterfly valve

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• 4The pressure of a liquid leaving the pump can be referred to as the ______.

  A.total head

  B.discharge head

  C.net positive suction head

  D.suction head

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• 5The gear and screw pumps are classified as______.

  A.variable stroke pumps

  B.multistage pumps

  C.positive displacement pumps

  D.triple-ported pumps

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• 6The dew point of air is reached when the wet bulb temperature is ______.

  A.twice the dry bulb temperature

  B.10℃ above the dry bulb temperature

  C.5℃ above the dry bulb temperature

  D.equal to the dry bulb temperature

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• 7If air at 95 ℃ dry bulb temperature and 50% relative humidity is conditioned to 75 ℃ dry bulb temperature and 50% relative humidity, it is an example of ______.

  A.cooling only

  B.cooling and humidifying

  C.cooling and dehumidifying

  D.adiabatic(绝热的) cooling

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• 8In order to achieve greater dehumidification(除湿) with an air conditioning system, you should ______. I. reduce the cooling coil temperature  II. increase the re-heater temperature

  A.I only

  B.II only

  C.Both I and II

  D.Neither I nor II

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• 9Oily water separators are used to ensure that ships don't discharge oil when pumping out ______.

  A.ballast water

  B.boiler water

  C.bilge water

  D.sewage water

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• 10When started, a complete oily water separating unit is first filled______. The oily water mixture is then pumped through the inlet pipe into the coarse separating compartment.

  A.with dirty water

  B.with clean water

  C.by oily water

  D.by mixed water

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