A:20
B:25
C:22.5
D:22.75
如图所示,这时“伏安法”测小灯泡的电阻所需的电路图,请在○中填上字母A和V,让它们变成电流表和电压表.
绿叶在光下合成淀粉的实验中,把盆栽的天竺葵放在暗处一昼夜,其目的是( )
It is a nice picture. Ann _________ it for me.