68. 變壓器有 3 個繞組如下圖，變壓器的匝數比為 N1:N2:N3＝1:2:3，當輸入電壓 V1(t)＝10sin(377t) V時，變壓器二次側 V2(t)與三次側 V3(t)的電壓為

(A)V3(t)＝-30sin(377t) V
(B)V2(t)＝20sin(377t) V
(C)V2(t)＝-20sin(377t) V
(D)V3(t)＝30sin(377t) V。