图示电路中，电压源=（   ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69505' and id < 4502637 and id<>'4502637' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69505' and id > 4502637 and id<>'4502637' order by id asc limit 5