.两个电阻串联，R1:R2=1:2,总电压为60v，则U1的大小为（   ）。

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SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69454' and id < 4497913 and id<>'4497913' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku_ where sourceid='69454' and id > 4497913 and id<>'4497913' order by id asc limit 5