A．v1＝16 m/s，v2＝15 m/s，t＝3s．        B．v1＝16 m/s，v2＝16 m/s，t＝2s．

C．v1＝20 m/s，v2＝20 m/s，t＝3s．        D．v1＝20m/s，v2＝16 m/s，t＝2s．

  • 答案
关闭