She every day.
A:do some reading
B:does some reading
C:did some read
D:did some reading
①电产生了磁,使电动机转动 ②磁产生了电,使小灯泡发光
③电动机是电源 ④转速越快,灯泡越亮.
如图为初中化学常见气体的发生与收集装置.