A:5π6
B:π2
C:π3
D:-π2
如图所示电路,电源电压恒定,R1为定值电阻,R2为滑动变阻器。闭合开关S后,滑动变阻器滑片P自b向a移动的过程中()
—Yes, you can. But you must know how to _________ it.