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【单选题】
超音速气流的加速性指的是（）。
A.
流速要加快，流管必须变细
B.
流速要加快，流管必须变粗
C.
流速要加快，流管可以不变
D.
流速与流管的横切面积无关
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参考答案：
参考解析：
刷刷题刷刷变学霸
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【单选题】第二篇 Flying the Hypert Skies A little airplane has given new meaning to the term "going hyper. " The Hyper-X recently broke the record for air-breathing jet planes when it traveled at a h...
A.
It indicated the birth of a very fast airplane.
B.
It was self-powered, so it lasted only 11 seconds.
C.
It can transportcargo quickly and cheaply to the brink of space.
D.
It is a major milestone in the journey of making a new type of very fast airplanes.