题目

— Did you know any Chinese, Joyce, before you arrived in Beijing?     — In fact, never _______ it. A. have I learned    B. I have learned    C. had I learned D. I had learned   答案：C考查倒装句及时态。  已知双曲线上存在两点关于直线对称，且的中点在抛物线上，则实数的值为_______________.