差动保护只能在被保护元件的内部故障时动作，而不反应外部故障，具有绝对的（    ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69378' and id < 4491493 and id<>'4491493' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69378' and id > 4491493 and id<>'4491493' order by id asc limit 5