在未受惊扰的条件下，石鳖会把它椭圆形的身体弓起一部分以方便呼吸。

When left alone, a chiton will lift part of its oval-shaped body to breathe.

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钙以方解石（碳酸钙）的形式存在于石灰岩、白垩、大理石、白云石、蛋壳、珍珠、珊瑚、钟乳石、石笋和许多海洋动物的壳体中。

In its compounds calcium has valence 2. It occurs in limestone, chalk, marble, dolomite, eggshells, pearls, coral, and many marine shells as calcium carbonate, or calcite;

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