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1.The mineral is used in the production of phosphoric acid and fertilizers.
这种矿物用于生产磷酸和肥料。
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2.The chalk was used as a writing surface for ancient Egyptians.
这种粉笔被古埃及人用作书写表面。
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3. The chalk was also used as a building material in ancient times.
这种粉笔在古代也被用作建筑材料。