I ____ to a zoo yesterday. [ ]
A. went
B. go
C. goes
A
一金属圆盘圆心恰好处于匀强磁场边界上,如图,当其沿桌面向右滚动时,金属圆盘中_____________ (填“会”或“不会”)产生感应电流,圆心处电势比边缘电势_____________。(填“高”“低”或“相等”)
电力变压器无微孩调压的分接开关有几种?