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Flying the Hypert1 Skies A little airplane has given new meaning to the term going hyper. The Hyper-X is an unmanned，experimental aircraft just 12 feet long. It achieves hypersonic speed using a special sort of engine known as a scramjet3.It may sound like something from a comic book，but engineers have been experimenting with scramjets since the 1960s. Out of the three experimental Hyper-X aircrafts built for NASA5，only one is now left.The agency has plans for another 11-second hypersonic flight，this time at 10 times the speed of the sound. 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。 | 
