① library ____ A.
② classroom ____ B.
③ teachers’ office ____ C.
下列说法比较合理的是( )
There are many different TV __________.
已知抛物线方程为y2=4x,直线l的方程为x﹣y+4=0,在抛物线上有一动点P到y轴的距离为d1,P到直线l的距离为d2,则d1+d2的最小值为( )