Only when he met the girl his aunt introduced to him that he had seen her before.
A. he realized
B. he did realize
C. realized he
D. did he realize
网友回答
A. he realized
B. he did realize
C. realized he
(答案→)D. did he realize
解析：本题考查倒装句。only所修饰的副词、介词短语或状语从句放在句首时要用倒装语序,将相应的助动词放到主语之前。