题型:问答题 在如图所示的电路中,电源电压不变,闭合开关s,电压表V1与V2示数之比为3:4,电流表A1的示数为1 A,电阻R1的功率是4W。若将电压表V2换成电流表A2,电流表A2的示数为3A,则下列计算结果不正确的是[ ]A.电阻R1与R2之比是3:4 B.电源电压是12VC.电阻R3的阻值是2ΩD.在如图所示的电路中,若通电1min,电阻R2消耗的电能是12J 查看答案
题型:问答题 All my friends like shopping in that supermarket. I wonder how long it _____. [ ]A. has openedB. has been open C. has been openedD. opened 查看答案