After a bird has flown from one tree to another, what trace does it leave in the air?

当一只鸟从一棵树飞到另外一棵树时，牠在空中留下什么痕迹呢？

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Instead of asking for volunteers at the gate to leave overbooked flights, Delta Air Lines now is enabling travelers to bid on the opportunity much earlier in the process.

与其在登机口说服游客自愿离开已经超售的航班，达美航空现在可以让旅行者提前为补偿的现金券竞价，并接受航班变更。

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Sometimes I imagine taking a page design that's too crowded and sticking it on a balloon, then blowing air in until everything on the page pulls apart to leave healthy gaps.

有时候我甚至想把一些非常拥挤的网页粘到气球上，然后一直吹气直到页面上所有东西之前都有足够的空隙。

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Whether her partner deserves better or worse is just one of the troubling question marks this superior mystery thriller dares to leave hanging in the air.

CNN: Review: 'Gone Baby Gone' is good, very good

But it does leave the question hanging in the air: is that it?

BBC: Tax Cuts Earn Limited Returns

Some revisionist history can leave the reader up in the air, wondering why, in the light of the historian's myth-busting, Catholic and Protestant bothered to quarrel with each other at all.

ECONOMIST: Irish history