下列叙述正确的是     A.纯净物一定是化合物             

下列叙述正确的是

    A.纯净物一定是化合物               B.混合物中可能只含一种元素

    C.某物质不是化合物就是单质         D.某物质含有氧元素,它一定是氧化物

答案

B

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