题目

Low-carbon lifestyle is of great benefit to improve the world environment．_____can be enjoyed from it until you have a deep understanding of it，however． A．Something            B．Nothing           C．Few               D．Much 答案：B图，过点A(-1，0)，斜率为k的直线l与抛物线C：交于P、Q两点． (1)若曲线C的焦点F与P，Q，R三点按如图顺序构成平行四边形PFQR，求点R的轨迹方程； (2)设P，Q两点只在第一象限运动，(0，8)点与线段PQ中点的连线交x轴于点N，当点N在A点右侧时，求k的取值范围．