题目

Success is often measured by the ability to overcome  adversity.But，it is often the belief of others that gives us the  courage to try. J．K.Rowling，author of the Harry Potter book series，began writing at the age of 6.In her biography，she remembers  with great fondness when her good friend Sean，whom she met  in secondary school，became the first person to encourage her   and help build the confidence that one day she would be a very good writer. “He was the first person with whom I really discussed my  serious ambition to be a writer.He was also the only person  有一固体混合物，可能由Na2CO3、CaCO3、Na2SO4、CuSO4、CaCl2、NaCl等混合组成．为检验它们，做了以下实验：（1）将固体混合物溶于水，搅拌后得无色透明溶液；（2）往此溶液中滴加过量的硝酸钡溶液，有白色沉淀生成；（3）过滤，将沉淀物置于稀硝酸中，发现沉淀部分溶解．试判断：①固体混合物中肯定有 ，②肯定没有 ，③可能有 ；对可能有的物质，可采取向滤液中滴加 溶液的方法来检验．