如图所示电路中，电源电动势为E.内阻为r，R1、R2、R3、R4均为定值电阻，

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='15523' and id < 2637964 and id<>'2637964' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='15523' and id > 2637964 and id<>'2637964' order by id asc limit 5