Chicago O'Hare is one of the world's busiest airports.

VOA: special.2009.01.12

Air traffic used to be everything flew to places local to it but now there's a system of hubs, Chicago O'Hare for instance or Newark where planes fly through.

以前的飞机都是飞往它的所属地,但现在的航空运输是一个由交通枢纽组成的系统，例如飞机会途经芝加哥O'Hare机场或Newark机场。

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