问题
选择题
Only when I left home to go to college ___ how much my mother had done for me.
A．did I realize
B．I realized
C．had I realized
D．I had realized
答案
答案：A
题目分析：句意：只有当我离开家去上大学，我才意识到妈妈为我做了多少事情。这句话用only+时间状语从句，放在句首，后面的主句用部分倒装，助动词提前，因为realize这个动作，就是发生在when I left home to go to college，所以用一般过去时，所以选A。