34下圖電路 由a-b 兩端點往左視入之戴維寧等效電壓 VTH 及戴維寧等效電阻 RTH 各為何?(A) VTH = 5V, RTH = 10Ω(B) VTH = 5V, RTH = 20 Ω(C) VTH = 10V, RTH = 10 Ω(D) VTH =10V, RTH = 20 Ω