有效接地系统的电力设备的接地电阻约为（）。

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='32667' and id < 2598230 and id<>'2598230' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='32667' and id > 2598230 and id<>'2598230' order by id asc limit 5