单项选择题
A.R=r1+r2+…+rn B.R=r1r2/(r1+r2) C.R=1/r1+1/r2+…+1/rn D.R=r2/r1+r3/r2+…+rn/rn-1
A.8.57Ω B.35Ω C.5Ω D.0.12Ω
A.110V B.66V C.44V D.22V