I failed again in the examination and only then how much time I had wasted.
A. I realized
B. I had realized
C. did I realize
D. had I realized
网友回答
A. I realized
B. I had realized
(答案→)C. did I realize
D. had I realized
解析：考查倒装句型。Only放句首时要求主句要使用部分倒装的句式。该句与前一句是并列关系，故事态一致/