在平面直角坐标系中,直线的参数方程为:(为参数).以原点O为极点,x轴的 正半轴为极轴,建立极坐标系,曲线的极坐标方程为:. (I)求曲线的直角坐标方程; (II)若曲线与直线交于,两点,点,求的最小值. 答案:解:(1); (2)3.Mr.Brown__________his hometown since he ____the army.( )A.has left;joinedB.has been away from;has joinedC.has been away from;joinedD.left;joined