如图所示,电源电压不变,R1=5Ω,R2=25Ω.(1)当S1、S2均闭合时,且甲、乙均为电压表,则U甲:U乙=_________,(2)当S1闭合,S2断开,且甲、乙均为电流表,则I甲:I乙=___________.