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。
The difference between an empty e-reader and a full one is just one attogram.
它们很容易丢失，当粘满你的显示器周围时又影响美观。
They're just to easy to lose and they're ugly when plastered all over your monitor.
在美国，居住区隔离非常极端，最好的公立学校满是致力于上大学的奋斗者，然而最差的学校则需要金属探测器来防止作弊。
In America, where residential segregation is extreme, the best public schools are stuffed with college-bound strivers, whereas the worst need metal detectors.
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