A balloon can fly in the air because hot air rises.

气球能在天空飞是因为热空气会向上升。

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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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We have learned to fly in the air like birds and swim in the sea like fish, but we have not learned the simple art of living together as brothers.

虽然我们已经学会了在空中像鸟儿一样飞翔，在海中像鱼儿一样游荡，但我们还是没有学会兄弟般一起生活的简朴艺术。

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There's the simple thrill of hitting a ball with a stick and watching it fly in the air.

WSJ: How Mom Plays the Game | Golf Journal

Among them was Air Memphis, which did not have a permit - after Egyptian authorities failed to respond to "adverse ramp inspection findings" - to fly in UK air space from April 1999 to May 2002.

BBC: The downed Egyptian plane was banned from Switzerland

During this period it did not apply for a permit and when it next applied for a permit to fly in UK air space, in May 2002, it was granted, and it has since been flying regularly in British air space with the full approval of British safety officials.

BBC: The downed Egyptian plane was banned from Switzerland