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The air sampled from the South Pole's clean air sector (a zone where air traffic, land vehicles, and even foot traffic is strictly limited) is touted as the cleanest air on Earth.

南极的洁净空气扇区(这个区域基本上没有任何空中，地面交通工具，甚至连行人都没有)被认为是地球上空气最干净的地方。

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In refugee camps on the periphery of the disaster zone, tent areas appear clean and orderly, with adequate supplies of food and clean water. There have been no reports of serious outbreaks of disease.

在灾区外围的难民营中，帐篷井然有序，净水与食物供应充足，至今还没有大规模疫情爆发的报道。

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In refugee camps on the periphery of the disaster zone, tent areas appear clean and orderly, with adequate supplies of food and clean water.

ECONOMIST: The earthquake in Sichuan

Villa are struggling in the Premier League, only one point above the relegation zone, and have failed to keep a clean sheet in each of their last 10 league games - of which they have won only two.

BBC: Aston Villa sign Spurs defender Kyle Walker on loan

Dropping out of the Euro-zone would be a drastic solution to the Greek tragedy, but it would be a clean solution.

FORBES: Greece Needs To Exit The Euro Zone