Only after you explained it to me it was not my teacher’s fault.A. I realizedB. had I rea

问题补充：

Only after you explained it to me it was not my teacher’s fault.

A. I realized

B. had I realized

C. realized I

D. did I realize

答案：

A. I realized

B. had I realized

C. realized I

(答案→)D. did I realize

解析：考查倒装结构。Only放在句首，后接状语从句，主句的主谓要倒装。根据句意用一般过去时，选D。