碳酸鈣的用法和樣例：
例句
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珍珠在幾種軟體動(dòng)物的貝殼中，圍繞著(zhù)一粒沙子或其他外來(lái)物質(zhì)形成的一種光滑、有色澤、具有不同顏色且主要是碳酸鈣的沉積物，被珍視為寶石
A smooth, lustrous, variously colored deposit, chiefly calcium carbonate, formed around a grain of sand or other foreign matter in the shells of certain mollusks and valued as a gem.
