图示直流电路中，由叠加定理可得电压U为（）。 

试卷相关题目

SQL Error: select id,body,options from ***_enewstiku where sourceid='32671' and id < 2598867 and id<>'2598867' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='32671' and id > 2598867 and id<>'2598867' order by id asc limit 5