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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.
【单选题】要求随时取得规定温度以上热水的建筑，对循环系统的设置要求是（）。
A.
无需设置回水管道
B.
保证支管中的热水循环
C.
保证干管和立管的热水循环
D.
以上说法均不正确