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【单选题】

Dreams of Flight The story of man's dream of flight, of his desire to reach the stars, is as old as mankind itself. According to Greek legend, Daedalus was the first man to fly. He and his son had been kept on an island, in order to escape, Daedalus shaped wings of wax (蜡) into which he stuck bird feathers. During their flight, his son flew too high and the sun melted the wax. He was drowned in the sea. The father was supposed to have continued his Night and reached Sicily, several hundred miles away. There is also an English legend of King Bladud who, during his rule in the ninth century B.C., used wings to fly. But his flight was short-lived and he fell to his death. The dream of flying continued, but in all the legends, the flier rose like a bird only to fall like a stone. It took hundreds of years that men flew up into the air and returned to earth safely. The first man to approach flying on a scientific basis was an Englishman who lived during the thirth century. He looked at the air about us as a sea, and he believed that a balloon could float on the air just as a boat did on water. Almost four hundred years later, an Italian priest applied his principle of air flight. He designed a boat, which would be held in the air by four hollow spheres (空心球). Each of the four balls was to be 20 feet in diameter (直径) and made of very thin copper. But his boat was never .built since it was not possible to make spheres of such thin metal and such size in those days. After studying the flight of birds and the movement of the air, a great scientist of the fifth century concluded that birds flew because they flapped (摆动) their wings and that it was possible for man to do the same. So a kind of flapping-wing flying machine was invented. Many men tried and failed to fly with flying machines. It was not until 1890 that people discovered why this method would never succeed-man could not develop sufficient power with his arms and legs. How did Daedalus manage to escape to Sicily, according to the passage?

A.
He killed the guards and got out of the island.
B.
A god came to rescue him and took him away.
C.
His son came to rescue him and took him away.
D.
He made wings of wax and flew away from the island.
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题目标签:摆动空心球直径
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参考解析:
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【多选题】传水辊传墨辊的摆动()。

A.
可以手动
B.
可随滚筒离合进行工作或停止
C.
只能自动进行
D.
不能手动
E.
不可随滚筒离合进行工作或停止

【单选题】纵隔摆动是指

A.
吸气时纵隔摆向患侧;呼气时移向健侧
B.
吸气时纵隔摆向健侧;呼气时移向患侧
C.
吸气时纵隔不动;呼气时移向健侧
D.
呼气时纵隔不动;呼气时移向患侧
E.
呼气时纵隔摆向健侧;呼气时不动