—Can you tell me _________________—Go along this road to the end. A . where is the supermarket? B . how can I go to the supermarket? C . how I can get to the supermarket? D . when I can get to the supermarket? 答案:C(09年上海十四校联考)如图所示,两个倾角相同的滑杆上分别套有A、B两个圆环,两个圆环上分别用细线悬吊着两个物体C、D,当它们都沿滑杆向下滑动时,A的悬线与杆垂直,B的悬线竖直向下。则下列说法中正确的是 ( ) A.A环与滑杆间没有摩擦力 B.B环与滑杆间没有摩擦力 C.A环做的是匀速运动 D.B环做的是匀加速运动