功率方向继电器可以通过判别（   ）实现。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69376' and id < 4491284 and id<>'4491284' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69376' and id > 4491284 and id<>'4491284' order by id asc limit 5