感应电流的条件是什么？
参考答案：①电路必须闭合
②只是电路的一部分导体在磁场中
③这部分导体做切割磁感线运动
The child didn't go to bed ___________ her mother came back. [ ]
A. when
B. until
C. after
D. as
雾中跟车行驶，要适当减小与前车的纵向距离。
