已知图中电压源吸收20W功率，则电压U=（）。 

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SQL Error: select id,body,options from ***_enewstiku where sourceid='32669' and id < 2598638 and id<>'2598638' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='32669' and id > 2598638 and id<>'2598638' order by id asc limit 5