题目

设O为坐标原点，直线与抛物线交于D，E两点，若，则C的焦点坐标为 A. (,0) B. (,0) C. (1,0) D. (2,0) 答案：B My brother ________ while he ________ his bicycle and hurt himself． [　　] A．fell; was riding B．fell; were riding C．had fallen; had ride D．had fallen; was riding