题目

Kevin studied very hard last term and as _____ result, he made _____ great progress. A . a; / B . /; a C . a; a D . /; / 答案：A设A（x1，y1），B（x2，y2）是抛物线y2=2px（p＞0）上两点，且满足OA⊥OB，则y1y2等于 ．