Only then that he had lost a good chance of achieving his dream.A. he realizedB. realize

问题补充：

Only then that he had lost a good chance of achieving his dream.

A. he realized

B. realized he

C. did he realize

D. will he realize

答案：

A. he realized

B. realized he

(答案→)C. did he realize

D. will he realize

解析：句意：知道那时他才意识到他错过了一个实现梦想的好机会。时态应为过去时。Only then放在句首需要部分倒装。故选C.