The difference between an empty e-reader and a full one is just one attogram.
一个空的电子阅读器和一个满的电子阅读器相比，差距仅有十的负十八次方克。
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According to John Kubiatowicz, from the University of California, Berkeley, the difference between an empty e-reader and a full one is just one attogram, or 10-18 of a gram.