题目

将一小块金属钠投入过量的硫酸铜溶液中，主要生成物是A.  Na2SO4和Cu            B.  NaOH和H2    C.  Cu(OH)2和H2                  D.  Na2SO4、Cu(OH)2和H2  答案：D解析: Helen is 15 years old, and Joan is 15, too. So Helen is ____ Joan. A. so old as    B. as older as  C. as old as