题目

—The trousers are only twenty dollars. Do you want________? —Yes, I do. A . these B . those C . them D . it 答案：C16．离子方程式Fe2O42-+xCu2O+10H+═2Fe2++yCu2++5H2O中，x的值为（　　）A．1B．2C．3D．4