选择题:Man has always wanted to fly. Even as long as eight hundred years ago, an Eng...

题目内容:

Man has always wanted to fly. Even as long as eight hundred years ago, an Englishman had tried. He made a ___1___ of wings from chicken feathers and fixed them to his shoulders. Then he jumped from a tall building. As you can imagine, he did not fly very far. ___2___, he fell to the ground and broke several bones. The first real attempt at flying took place in France in 1783. The two Mongolian brothers knew that hot air rose. If they could fill a large balloon ___3___ hot air, they thought it would rise into the air and fly. They were right. They made a very large hot air balloon of cloth and paper. It measured ten meters in diameter. They filled it with hot air and the balloon got two hundred meters into the air. It fell to earth about three kilometers away. At the next attempt, they ___4___ for a balloon to carry passengers. We do not know what the passengers felt about the trip as they were a cock, a duck, and a sheep. But we ___5___ know that the trip lasted eight minutes and the animals landed safely. 根据短文内容,在A、B、C、D、E五个选项中,选出最佳答案填入文中【4】处。().

A Instead B pair C do D arranged E with

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电动机的型号为YMB-100S,其中的M表示采煤机用。()A.正确B.错误

电动机的型号为YMB-100S,其中的M表示采煤机用。()A.正确B.错误

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An old man died and left his son a lot of money. But the son was a foolish yo...

An old man died and left his son a lot of money. But the son was a foolish yo...

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黏土看上去似乎是一种肥沃度差、由多种矿物质组成的混合物,但却可能是地球生命的起源地。在模拟古代的海水中,黏土会形成水凝胶——由大量可吸收液体

黏土看上去似乎是一种肥沃度差、由多种矿物质组成的混合物,但却可能是地球生命的起源地。在模拟古代的海水中,黏土会形成水凝胶——由大量可吸收液体的微小空间构成(像海绵一样)。过去几十亿年里,被禁锢在这些空间里的化学物质可能发生了复杂的反应,从而形成了蛋白质、脱氧核糖核酸以及最终生成活细胞的各种系统。黏土形成的水凝胶可能对上述化学过程起到了禁锢和保护的作用,直至发育出将活细胞包裹住的细胞膜为止。这段文字

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