阅读理解

阅读下列短文，从每题所给四个选项(A，B，C和D)中，选出最佳选项．

　　Man always wanted to fly. For hundreds of years they watched birds flying and wished that they could fly too. Birds fly very easily. They spread(展开) their wings(翅膀) and float (漂浮) on the air. The air keeps them up for many hours.“If birds and kites can stay up in the air perhaps we can too.”they thought.

　　At first they made wings like birds. Then they jumped off high buildings in order to fly. Many men did this but they all failed. After many failures (失败) they stopped trying to fly with wings. Then two brothers tried another way. They tried balloons (气球).“Hot air is lighter than cold air ”they said “That is why hot air goes upwards. If we fill a balloon with hot air it will go upwards.”

　　After many experiments they made two men go up in a balloon full of hot air. A great crowd of people watched. The balloon rose to a height (高度) of 900 metres. The wind blew it along for nine kilometers. Then it came gently back to earth. For the first time man traveled through the air!

1．Hundreds of years ago men realized that ________.

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A．birds fly easily because there is air

B．birds fly easily because they are small

C．birds fly easily because they have wings

D．birds fly easily because they are light

2．When some men tried to fly with wings ________.

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A．only a few of them succeeded

B．only the two brothers succeeded

C．many of them succeeded

D．none of them succeeded

3．Which of the following did men first think of when they wanted to fly?

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