题目

 -- What happened on your way? We have been awaiting you for some time.    -- Well, I could have come here in time for the meeting, but I ____ a flat tire halfway. A. have                        B. had                                 C. would had                       D. had had 答案：B 一元二次函数的解为（ ）A. =-1， =-2 B. =1，=2C. =0，=1 D. =0，=2