题目

某理想变压器的原、副线圈按如图所示电路连接，图中电表均为理想交流电表，且R1=R2，电键S原来闭合。现将S断开，则电压表的示数U、电流表的示数I、电阻R1上的功率P1、变压器原线圈的输入功率P的变化情况分别是A．U增大          B．I增大C．P1减小          D．P增大 答案：A----______number of cars on the roads is growing too fast.----I agree with you. ______ number of problems have appeared already.A. A, A B. The , TheC. The ,a D. A, the