题目

(07年广东卷理)在直角坐标系xOy中,有一定点A（2，1）。若线段OA的垂直平分线过抛物线的焦点，则该抛物线的准线方程是______; 答案：答案：;解析：OA的垂直平分线的方程是y-，令y=0得到x=; --- It’s said that there are more than 1 million citizens in the county. ---Exactly. One reason is that people are            into it in great numbers. A. breaking         B. filling        C. pouring         D. hurrying