数年前，即使是三分之一人类感知范围也是非常了不起了。

A few years ago even a third of the range of human perception was impressive.

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科学家把地球上可饮用的淡水——包括湖泊、河流和蓄水层的水统称为“深海”，人类每一年能够使用大约三分之一的“深海”。

Of all the fresh water accessible in lakes, rivers and aquifers — what scientists call “blue water” — humankind uses about one-third every year.

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由于猫科动物的城市化（和它们的排泄物），几乎三分之一的人类已经有慢性的潜在的，但似乎无伤大雅的弓形虫感染。

Thanks to the urbanization of cats (and their feces), almost a third of the human population now has a chronic, latent, and seemingly innocuous Toxo infection.

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