问题补充:
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
答案:
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。