（  ）是促成绝缘老化的直接原因。 

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69485' and id < 4500654 and id<>'4500654' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69485' and id > 4500654 and id<>'4500654' order by id asc limit 5