天平的制动系统由秤盘、吊耳、空气阻尼器等部件组成。
参考答案:错
Books of this kind ____ well.[ ]
A. sell
B. sells
C. are sold
D. is sold
A.0至0.5ms内,电容器C正在充电
B.0.5ms至1ms内,电容器上极板带正电荷
C.1ms至1.5ms内,Q点比P点电势高
D.1.5ms至2ms内磁场能在减少,磁感应强度增大