把Ba(OH)2溶液滴入明矾溶液中，使SO42- 全部转化成BaSO4沉淀，此时铝元素的主要存在形式是（   ）　

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19957' and id < 1732637 and id<>'1732637' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='19957' and id > 1732637 and id<>'1732637' order by id asc limit 5