private void btXetHocBong_Click(object sender, EventArgs e)
        {
            HocBong_DSSV HB_DSSV = new HocBong_DSSV();

            HB_DSSV.TopLevel = false;
            HienThi.Controls.Clear();
            HienThi.Controls.Add(HB_DSSV);
            HB_DSSV.Show();
        }
 private void btXetHocBong_Click(object sender, EventArgs e)
 {
     HocBong_DSSV HB_DSSV = new HocBong_DSSV();
     HB_DSSV.TopLevel = false;
     HienThi.Controls.Clear();
     HienThi.Controls.Add(HB_DSSV);
     HB_DSSV.Show();
 }