定时限过电流保护是依靠（   ）获得选择性。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69376' and id < 4491247 and id<>'4491247' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69376' and id > 4491247 and id<>'4491247' order by id asc limit 5