1. 如右圖,A、B、C、D、E、F 為圓 O 上的點,
(A) ∠C = ∠D < ∠E = ∠F (B) ∠C = ∠D > ∠E = ∠F (C) ∠C = ∠D = ∠E = ∠F(D) ∠C < ∠D < ∠E < ∠F