题目

In our university there are several big parks ____we students can go to enjoy the beautiful scenery．        A．to which B．at which   C．from which      D．in which 答案：A已知A、B为两种黑色粉末，D为红色单质，A、B、C、D四种物质之间的转化关系如图所示。请回答：(1)C的化学式为______。(2)反应①的化学方程式为__________________________，该反应中被还原物质的化学式为______。