It was requested that the play ____again.

A．should put on

B．would put on

C．be put on

D．put on

变压器充电时，励磁电流的大小与断路器合闸瞬间电压的相位角有关，当=（）时，不产生励磁涌流；当=（）时，合闸磁通由零增至2m，励磁涌流最大。