I failed in the final 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?

 It’s too bad that I failed in the math exam. If only I ______ hard at it!

I failed in the spoken examination last term and only then _______ the importance of practicing speaking English.

A. I had realized    B. had I realized      C. I did realize   D. did I realize

—Oh, I failed in the exam.

—_______.You still have chance.

A. Take your time　            B. Don’t lose heart

C. Don’t lose your heart　    D. No pains, no gains

I failed in the final 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