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[职称英语阅读理解] 2015年职称英语理工类A级阅读理解试题以及答案(5)

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  Flying the Hypert1 Skies

  The Hyper-X2 recently broke the record for air-breathing jet planes when it traveled at a hypersonic speed of seven times the speed of sound.Thats about 5,000 miles per hour.At this speedyoud get around the worldflying along the equatorin less than 5 hours.

  For an engine to burn fuel and produce energyit needs oxygen.A jet enginelike those on passenger airplanesgets oxygen from the air.A rocket engine typically goes faster but has to carry its own supply of oxygen.A scramjet engine goes as fast as a rocketbut it doesnt have to carry its own oxygen supply.A scramjets special design allows it to obtain oxygen from the air that flows through the engine.And it does so without letting the fast-moving air put out the combustion flames. Howevera scramjet engine works properly only at speeds greater than five times the speed of sound.A booster rocket carried the Hyper-X to an altitude of about 100,000 feet for its test flight.The aircrafts record-beating flight lasted just 11 seconds.Although the little planes self-powered flight lasted only 11 secondsthat brief journey on March 27 makes a major milestone on the way to a new breed of very fast airplanescomments Werner J.A.Dahm of the University of Michigan in Ann Arbor4.In the futureengineers predictairplanes equipped with scramjet engines could transport cargo quickly and cheaply to the brink of space. Such hypersonic jets could potentially carry passengers anywhere in the world in just a few hours.

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