River filtration systems purify surface water flowing through this system to some extent, but degree of purification is not known.

河流渗滤系统对入渗的地表水有一定的净化作用，过去人们很少从理论上研究河流渗滤系统对污染河水的净化作用。

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So at the end of the day, you can figure out, OK, now when I reach a certain degree of purification, here's how much of the stuff I end up with.

在今天结束的时候，你们就可以知道这点，好，现在当我达到某一纯度的时候，这是我得到的物质的量。

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So then, in a practical way, it's possible to walk quite far along the distillation, the coexistence curve, and distill to really a high degree of purification.

如此反复，实际过程中，可以沿着，共存曲线蒸馏很久，然后提纯到一个很高的纯度。

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