For anyone who doubts that the texting revolution is upon us, consider this: The average 13-to 17-year-old sends and receives 3,339 texts a month—more than 100 per day, according to the Nielsen Co.

如果有人对短信革命的到来表示怀疑，那就想想看：据尼尔森公司的数据，13至17岁的人平均每月收发3339条短信——每天超过100条。

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The average rotational latency is one-half of a revolution of the disk platter.

平均旋转等待时间指的是磁盘旋转一半的时间。

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Rice paddies in the Senegal valley, for example, yield 50 percent more than the global average — and, unlike Asia, this chunk of the tropics has yet to see its green revolution.

比如，塞内加尔河谷的水稻产量比全球平均产量高50%，与亚洲不同，大面积的热带土壤可孕育出绿色作物。

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Before the 19th-century Industrial Revolution, the average carbon dioxide concentration worldwide was about 280 parts per million.

CNN: CO2 levels hit new peak at key observatory

Scientists estimate that the average acidity of surface ocean waters worldwide is now about 30% higher than before the Industrial Revolution.

BBC: Arctic Ocean 'acidifying rapidly'