Only when I got here that I had made a big mistake.
A. did I realize
B. I realized
C. I have realized
D. have I realized
网友回答
(答案→)A. did I realize
B. I realized
C. I have realized
D. have I realized
解析：考查倒装结构。本题考查only + 状语从句 + 主谓倒装，主句用过去完成时，从句用一般过去时，选A。