双速三相交流鼠笼式异步电动机常用的改变转速的方法是（   ）。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69445' and id < 4497264 and id<>'4497264' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69445' and id > 4497264 and id<>'4497264' order by id asc limit 5