充电时要观察电池的（）变化，有异常要停电处理。
A.电解液的比重
B.电解液的温度
C.电池的端电压
D.充电电流
参考答案：A, B, C, D
You should give up ______ on the computer for so long a time. It's harmful to your health. [ ]
A. play
B. to play
C. playing
D. plays
A．时刻t线圈中电流的瞬时值icosωt
B．线圈中电流的有效值I
C．线圈中电流的有效值I=
D．线圈消耗的电功率P
cosωt
