当点P在圆上变动时,它与定点相连,线段PQ的中点M的轨迹方程是 A. B. C. D. 答案:【答案】B【解析】设,,利用中点坐标公式可以求出,代入圆方程中,可以求出中点M的轨迹方程.设,,因为M是线段PQ的中点,所以有,点P在圆上,所以有,故本题选B.
The more ______ people drive, the ______ traffic accidents there ill be. A. careful; less B. careful; fewer C. carefully; fewer D. carefully; more