现在有一不纯的氧化铁样品（里面只有一种杂质），经测定样品中氧

现在有一不纯的氧化铁样品（里面只有一种杂质），经测定样品中氧元素的质量分数为28%，则里面含有的杂质可能是

A．氧化铜 B．碳酸钙 C．氧化镁 D．氧化铝

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现在有一不纯的氧化铁样品（里面只有一种杂质），经测定样品中氧

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