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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In smoggy weather, the machine would breathe in the air in front of the bike and blow out a stream of clean air toward the biker's face.

在有雾霾的天气里，机器会吸进自行车前面的空气，然后向骑自行车的人的脸上吹出一股清新的空气。

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For example, in fair weather, the air pressure is generally high, the air is still, and often full of dust.

例如，在晴朗的天气里，气压通常很高，空气是静止的，而且经常含有灰尘。

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The group's recent "State of the Air" report said Pittsburgh has the worst short-term fine particle pollution in the country.

VOA: special.2009.07.13

And it's the windows in the firmament that are opened--those waters are allowed to rush in and dissolve that air bubble.

而在天空上有个口,水可以从中涌入，溶解这些气泡。

耶鲁公开课 - 旧约导论课程节选

But it can be acquired in the air, from patients that are from- from other individuals that are infected.

天花会通过空气传播,通过病人和其他感染者呼出的空气传播

耶鲁公开课 - 生物医学工程探索课程节选

Numerous helicopter companies (most based in Lihu'e) offer up-in-the-air jaunts over waterfall-striped Mt Wai'ale'ale, the island's central shield volcano and one of the wettest spots on Earth, and the sheer-hewn sea cliffs of the Na Pali coast, accessible otherwise only by ocean kayak.

BBC: Hawaii for beach haters

The Seawolf submarine, the C-17 transport aircraft, several different air-to-ground and air-to-air missiles are in the cross-hairs.

CENTERFORSECURITYPOLICY: Center for Security Policy | FOR A CREDIBLE DEFENSE POSTURE IN THE FUTURE, INVEST IN THE B-2 TODAY

The problem is--assuming the F-35 sees the light of day in a timely manner--that this aircraft simply doesn't do the job in air-to-air combat that the F-22 does, nor does it have the F22's ability to penetrate sophisticated defenses.

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