Not until he failed in the last examination he should have spent more time on study.
A. did he realize
B. he realized
C. did he not realize
D. he didn’t realize
网友回答
(答案→)A. did he realize
B. he realized
C. did he not realize
D. he didn’t realize
解析：考查倒装句：句意：直到他在最后一次考试中失利，他才意识到他应该在学习上多花些时间。Not until引导时间状语从句置于句首，后面的主句用部分倒装，以前前面是not until，后面是肯定句，选A。