private void button1_Click(object sender, EventArgs e)
        {
            ThemThongTinBenhNhan bn = new ThemThongTinBenhNhan();

            bn.ShowDialog();
            this.Hide();
        }
        private void thêmBệnhNhânToolStripMenuItem1_Click(object sender, EventArgs e)
        {
            ThemThongTinBenhNhan x = new ThemThongTinBenhNhan();

            x.ShowDialog();
        }