题目

完形填空阅读下面短文，掌握大意，然后从各题所给的四个选项中选出一个最佳选项。    Last Saturday, Tony went to see Benny. But he didn't know   1  Benny lived. On the way, he   2  in front of a yellow house, and asked an old woman the  3   to Benny's house. “His house is not far from my house,” said the woman. “It's behind the trees. But you can't get there    4   .You can go there by bus. It'll  5  you hours to get there   6   foot.” “What's wrong with her?” Tony    7    .“I can see Benny's house from here now. It's 过抛物线x2=4y的焦点作直线l交抛物线于A，B两点，分别过A，B作抛物线的切线l1，l2，则l1与l2的交点P的轨迹方程是（　　） A、y=-1B、y=-2C、y=x-1D、y=-x-1