A:I'm not invited
B:I won't be among the invited
C:they won't invite me
D:they didn't invite me
用伏安法测一节干电池的电动势E和内阻r,所给的器材有:
A.电压表V:0~3~15V
B.电流表A:0~0.6~3A
C.滑动变阻器R1(总阻值20Ω)
D.滑动变阻器R2(总阻值100Ω)
E.开关S和导线若干
下列四个半球的名称依次是( )