To fly, of course, is the fastest way, but you can't see anything during your stay in the air but the blue sky and white clouds.

飞行，当然，是最快的方式，但是在你停留在空中的时候，你看不到任何东西，除了蓝天和白云。

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He found that one falcon had already been able to fly high in the sky, while the other one was staying at the branch of a tree quietly without moving.

他发现一只猎鹰已经能在高空中飞行，但另一只静静地待在树枝上一动不动。

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The father smiled and said, "The role of the string was not stopping the kite from flying higher, but helping it stay in the sky, because the kite itself can't fly up."

父亲笑着说：“线的作用不是阻止风筝飞得更高，而是帮助它留在天空中，因为风筝本身不能飞起来。”

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The old system, he said, is outdated, doesn't use all of the sky and directs planes to fly farther and longer than they need to.

CNN: Study: Flight delays to get worse as economy improves