private void btNganhDaoTao_Click(object sender, EventArgs e)
        {
            DanhSachNganhDaoTao DSNDT = new DanhSachNganhDaoTao();

            DSNDT.TopLevel = false;
            HienThi.Controls.Clear();
            HienThi.Controls.Add(DSNDT);
            DSNDT.Show();
        }
 private void btNganhDaoTao_Click(object sender, EventArgs e)
 {
     DanhSachNganhDaoTao DSNDT = new DanhSachNganhDaoTao();
     DSNDT.TopLevel = false;
     HienThi.Controls.Clear();
     HienThi.Controls.Add(DSNDT);
     DSNDT.Show();
 }