We have supper 6:00 in the evening. [ ]
A. at
B. in
C. on
答案：A
光补偿点
A．副线圈中电压表的读数为55V
B．副线圈中输出交流电的周期为0.01s
C．原线圈中电流表的读数为0.5A
D．原线圈中的输入功率为110W
W