线路始端电压和末端电压的代数差称为(    )。  

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69462' and id < 4498661 and id<>'4498661' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69462' and id > 4498661 and id<>'4498661' order by id asc limit 5