Only when I left my parents for America how much I loved them.A. I realizedB. I had reali

问题补充：

Only when I left my parents for America how much I loved them.

A. I realized

B. I had realized

C. had I realized

D. did I realize

答案：

A. I realized

B. I had realized

C. had I realized

(答案→)D. did I realize

解析： 考查倒装。Only+ when引导的时间状语从句放在句首时，主句要部分倒装，所以排除A,D；C项表示意识到我有多爱他们这一动作发生在left之前，不符合句意，所以选D。