Mr. Bright is used to ____ (drink) some milk before going to bed.
如图,已知Rt△ABC中,∠C=90°,BC=3,AC=4,则sinA的值为( )
如图示电路中,当开关S闭合,甲、乙两表是电压表时,示数之比U甲:U乙=3:2,当开关S断开,甲、乙两表都是电流表时,则两表的示数之比I甲:I乙为()