有三个电阻R1、R2、R3并联，则并联总电阻R与R1、R2、R3的关系是（)。A.R=R1＋R2＋R3B.1／R=1／R1＋1／R2＋1／

有三个电阻R1、R2、R3并联，则并联总电阻R与R1、R2、R3的关系是()。

A.R=R1+R2+R3

B.1/R=1/R1+1/R2+1/R3

C.R=1/R1+1/R2+1/R3