We decorate the room flowers and red lanterns to celebrate the New Year.
读下图,完成小题。
在豌豆杂交实验中,高茎与矮茎杂交得F1,F1自交所得F2中高茎和矮茎的比例为787:277,上述实验结果的实质是
如图所示电路,当开关S闭合,甲乙两表均为电压表,两表读数之比U甲:U乙=3:1,则R1:R2=____ ;当开关S断开,甲乙两表均为电流表,两表读数之比I甲:I乙=____ .