南极地区泛指( )
A:南极大陆及周边的岛屿
B:60°E以南的地区
C:60°N以南的地区
D:60°S以南的地区
— Mum, I've got a chance to be an exchange student to the UK next year!
— Really? That's just ________ to be true. Anyway, congratulations, baby!
如图所示,已知电源电压为U,三个电源的阻值分别为R1、R2和R3,求:
①当S1、S2均断开,电流表和电压表的示数;
②当S1、S2均闭合时,电压表和电流表的示数.
____(mine)