28.鬆緊套(turnbuckle)之接頭(terminal fitting)到套管上，接頭之螺牙最多可露幾牙？(A)六牙(B)五牙 (C)三牙 (D)兩牙

9. In general, increasing the cross sectional area of an electrical cable (A)enables it to carry more current. (B)enables it to carry more voltage. (C)increases its resistance. (D)no effect on the resistance and current.