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

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• 1A 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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• 2Which 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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• 3The 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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• 4The 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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• 5A feed pump for an auxiliary boiler might lose suction if the ______.

  A.boiler water level is low

  B.feed-water is too hot

  C.boiler steam demand is low

  D.feed-water is too cold

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• 6Which of the following conditions must exist for heat to flow from one object to another、

  A.The two objects must be in physical contact.

  B.The two objects must be the same size.

  C.There must be an existing temperature differential.

  D.There must be an existing weight differential.

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• 7The 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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• 8If 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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• 9In 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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• 10Oily 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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