10.如【圖10】所示電路，戴維寧等效ETH及RTH分別為多少？(A)ETH= 4V; RTH=3Ω(B)ETH= 20V ; R TH=7Ω(C)ETH= 4V ;RTH=7Ω(D)ETH= 20V;RTH=3Ω
