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 speed，youd get around the world flying along the equator in less than 5 hours.
For an engine to burn fuel and produce energy，it needs oxygen.A jet engine，like those on passenger airplanes，gets 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 rocket，but 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. However，a 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 seconds，that brief journey on March 27 makes a major milestone on the way to a new breed of very fast airplanes，comments Werner J.A.Dahm of the University of Michigan in Ann Arbor4.In the future，engineers predict，airplanes 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.
词汇7haipE5sCnik 5bu:stEp
equator n.赤道 milestonen.里程碑
scramjetn.超音速燃烧冲压式， cargon.货物
combustionn.燃烧 brinkn.边缘
1. The Hyper-X broke the record because
B it flew along the equator.
D it traveled at a supersonic speed.
A A jet engine that gets oxygen from the air.
C A rocket engine that carries its own supply of oxygen.
3. What is NOT true about the scramjet engine?
B It extracts oxygen from the air that flows through the engine.
D It doesnt carry its own oxygen supply.
A It indicated the birth of a very fast airplane.
C It can transportcargo quickly and cheaply to the brink of space.
5. What has NASA planned to do?
B To make three more Hyper-X experiments.
D To make the aircraft fly higher and longer.
1. C Hyper-X之所以打破纪录是因为它的飞行速度是音速的7倍。它不是第一架空气喷气式飞机，也不是第一架超音速飞机，所以A和D都不对。Hyper-X的试飞并未绕赤道飞行，所以B也是错误的选择。
3. A 根据第五段内容，B、C、D都是正确的说法。第四段最后一句告诉我们，A的说法是不正确的。
5. A 答案可在最后一段找到。