The pressure range between the system cut in and cut out pressures in a refrigeration unit is known as_______.

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• For a L√Opurifier, if the back pressure of the oil outlet is too high, the interface between oil and water in the bowl will （）.

  A . be interrupted B . move downwards C . move outwards D . retain original positio

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• （） are used to limit the pressure in any particular portion and mainly control the pressure after the valve.

  A、Relief valves B、Safety valves C、Check valves D、Reducing valves

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• The （） is a crystal which, under pressure, produces an electric current which varies with the pressure.

  A . alternator B . glass thermometer C . burdon tube D . piezoelectric pressure transducer

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• To maintain design discharge pressure from a centrifugal pump, the design clearance must be maintained between the （）.

  A . shaft and impeller B . motor and pump shaft C . casing and impeller wearing rings D . lantern ring and impeller

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• The pump discharge pressure will be considerably higher than the pressure at the （）.

  A . pump entry branch B . outlet pipe C . impeller D . None of the above is true

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• That is the existing product range. "product range" means product portfolio.

  A . 正确 B . 错误

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• What is the numerical range of char？（）

  A .  0…32767 B .  0…65535 C .  –256…255 D .  32768…32767 E .  Range is platform dependent.

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• The major difference between the discharge and suction valves installed in most low pressure, reciprocating air compressors is that（）

  A、one valve seats upwards, while the other seats downwards B、the reed valves used on the discharge are made substantially thicker and heavier than thesuction valves C、the suction valve springs exert a greater tension than the discharge valve springs D、the discharge valve springs exert a greater tension than the suction valve springs

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• The design of for a flash type evaporator is of critical importance because it must provide an optimum feedwater spray pattern that facilitates the flashing process, and it must also maintain a pressure differential between successive stages（）

  A . condenser B . flashing device C . lashing device D . vacuum pum

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• Water evaporates or steam condenses at the saturation temperature, which depends upon the pressure, the higher the pressure （） the saturation temperature.

  A . the more B . the higher C . the lower D . the highest

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• In a compression refrigeration plant the refrigerant is under low pressure in the （） and under high pressure in the （）.

  A . compressor；condenser B . condenser；evaporator C . throttle valve；evaporator D . evaporator；condenser

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• If a large difference exists between the compressor discharge pressure and the pressure corresponding to the existing condensing temperature in a refrigeration system, you should（）.

  A . increase the flow of the cooling water through the condenser B . adjust the high pressure cutout to maintain the desired pressure C . open the hot gas bypass temporarily to reduce capacity D . purge non-condensable gases to reduce the excess pressure

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• An axial piston, variable stroke pump is used in a vessels hydraulic steering gearUnder pressure, oil continually leaks out from between the valve plate/cylinder barrel and will（）.

  A . cause loss of hydraulic oil from the system B . result in extreme damage to the pump C . cause damage to the pump ff not continually drained from the pump casing D . result in the system high side pressure to substantially drop off

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• The vapor pressure of a gas is the pressure necessary to keep it in a(n)（）.

  A . soluble state B . solid state C . liquefied state D . inert state

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• What is the substance called which can readily be converted from a liquid into a vapor, and also from a vapor into liquid with a reasonably narrow range of pressure?（）

  A . Refrigerator B . Refrigerant C . Cooling medium D . Brine

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• The luminous range of a light takes into account the（）.

  A . glare from background lighting B . existing visibility conditions C . elevation of the light D . observer's height of eye

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• An increased pressure differential between the inlet and outlet of a strainer usually indicates the strainer is （）

  A . holed B . fouled C . clean D . dry

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• Which one of the binary number ranges shown below corresponds to the value of the first octet in Class B address range?（）

  A . 10000000-11101111 B . 11000000-11101111 C . 10000000-10111111 D . 10000000-11111111 E . 11000000-10111111

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• 207. The greater the pressure difference between a high and a low pressure center, the ______ .

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• 194.The local differences between upward pressure of buoyancy and the ship’s local weight give rise to______.

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• For a L.Opurifier, if the back pressure of the oil outlet is too high, the interface between oil and water in the bowl will _____.

  A.be interrupted B.move downwards C.move outwards D.retain original position

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• The basic principle of radar is illustrated by what happens when one shouts in a e. The echoof the shouting 11 the walls helps a person determine the size of i cave. With radar, however , the waves are radio waves instead of 12 waves. dio waves travel 13 the speed of light, about 300,000 kilometers in a second. A lar set 14 a short burst of radio waves. Then it receives the echoes 15 when waves bounce (Silt) off objects. By determining the time it 16 for the echoes to imi to the radar set, a trained technician 17 determine the distance between the [ar set and other objects. The word "radar", 18 , gets its name from the term dio detection and ranging." "Ranging" is the term for detection of the 19 between object and the radar set.

  Besides being of critical importance to pilot, radar is 20 for air traffic control, tracking ships at sea, and for tracking weather systems and storms. 11. A.through B.for C.on D.against

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• The coast of the State of Maine is one of the most irregular in the world. A straight line running from the southernmost coastal city to the northernmost coastal city would measure about 225 miles. If you followed the coastline between these points, you would travel more than ten times as far. This irregularity is . the result of what is called a drowned coastline. ______【46】. At that time, the whole area that is now Maine was part of a mountain range that lowered above the sea. As the glacier (冰川) descended, however, it expended enormous force on those mountains, and they sank into the sea.

  As the mountains sank, ocean water charged over the lowest arts of the remaining land, forming a series of twisting inlets and lagoons (咸水湖) . The highest parts of the former mountain range, nearest the shore, remained as islands. ______【47】Marine fossils found here were 225 feet above sea level, indicating the level of the shoreline prior to the glacier. The 2, 500-mile-long rocky coastline of Maine keeps watch over nearly two thousand islands. Many of these islands are tiny and uninhabited, but many are home to thriving communities. Mt. Desert Island is one of the largest, most beautiful of the Maine coast islands. Measuring 16 miles by 12 miles, Mt. Desert Island was essentially formed as two distinct islands. ______【48】. For years, Mt. Desert Island, particularly its major settlement, Bar Harbor, afforded summer homes for the wealthy. Recently though, Bar Harbor has become a rapidly growing arts community as well. But the best part of the island is the unspoiled forest land known as Acadia National Park. Because the island sits on the boundary line between the temperate (温带) and sub-Arctic zones, the island supports the plants and animals of both zones as well as beach, inland , and alpine (高山 的) plants. ______【49】The establishment of Acadia National Park in 1916 means that this natural reserve will be perpetually available to all people, not just the wealthy. Visitors to Acadia may receive nature instruction from the park naturalists as well as enjoy camping, cycling, and boating. Or they may choose to spend time at the archeological museum, learning about the Stone Age inhabitants of the island. The best view on Mt. Desert Island is from the top of Cadillac Mountain. ______【50】. From the summit, you can gaze back toward the mainland or out over the Atlantic Ocean and contemplate the beauty created by a retreating glacier. A. It also lies in a major bird migration lane and is a resting spot for many birds. B. Mt. Desert Island is one of the most famous of all of the islands left behind by the glacier. C. The wealthy residences of Mt. Desert Island selfishly keep it to themselves. D. The term comes from the activity of the Ice Age. E. This mountain rises 1, 532 feet, making it the highest mountain on the Atlantic seashore. F. It is split almost in half by Somes Sound, a deep and narrow stretch of water seven miles long. (46)

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• The less palatable range plants（）

  A．are often harmful to cattle health B．contain little natural ingredients C．are low in vitamins and minerals D．are not suitable for the cattle to eat at all

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