问题
选择题
I failed in the examination last term and only then ____ the importance of studies.
A．I realized
B．I had realized
C．had I realized
D．did I realize
答案
答案：D
句意：上学期期末考试我没考及格，只在那时我才意识到学习的重要性。Only修饰状语then位于句首时需使用部分倒装，本句的时态应使用一般过去式。