某物质中只含有一种元素，则该物质请选择DCBA4I'n;M3f-t7D1H:\5u1}/k'D*E(E
A．一定是单质-t7D1H:\5u1}/k'D*E(E
B．一定是混合物-t7D1H:\5u1}/k'D*E(E
C．一定是纯净物-t7D1H:\5u1}/k'D*E(E
D．一定不是化合物-t7D1H:\5u1}/k'D*E(E