题目

—We’ll make a trip to Hainan Island next weekend. Will you go with us? —No, I can’t _____ it at present.     A.afford      B.save      C.offer        D.accept 答案：A抛物线的定点在坐标原点，焦点是双曲线x22-y22=1的右焦点，则抛物线的标准方程是 ．