看看它的工作原理：在市面上流通的每张美元钞票上，都有一个10位或11位的唯一的序列码。

Here's how it works. On every U.S. dollar bill in circulation is a 10- or 11-digit serial code that is unique to that bill.

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介绍上流式厌氧滤池的结构原理，并对上流式厌氧滤池工艺设计方法和设计参数进行总结。

The paper presents the structure principle of anaerobic upflow filler. and makes a summary for its technical DE sign and design parameter.

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