Not until they left school how much their teachers loved them and helped them.
A. they realized
B. did they realized
C. they would realized
D. had they realized
网友回答
A. they realized
(答案→)B. did they realized
C. they would realized
D. had they realized
解析：考查not until的倒装句型。Not until位于句首，句子发生部分倒装，排除AC, 动作realize和left同时发生，故选择答案B。句意：直到他们离开学校后他才意识到他们的老师是多么的爱他们，帮助他们。