During the nineteenth century, a unit of chemical currency called the mole came into use.

十九世纪时，人们开始使用一种称为摩尔的化学通用单位。

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During the nineteenth century, a unit of chemical currency called the mole came into use.

十九世纪时，人们开始使用一种称为摩尔的化学通用单位。

youdao