Only when I left for America how much I missed my parents.
A. I realized
B. did I realize
C. I had realized
D. had I realized
网友回答
A. I realized
(答案→)B. did I realize
C. I had realized
D. had I realized
解析：only+状语位于句首句子采用部分倒装，根据句子意思看描述过去的事情应用一般过去时态。句意：只有当我到了美国我才意识到我多么想念我的父母。