private void button2_Click(object sender, EventArgs e)
        {
            btnformchinh form = new btnformchinh();

            form.Show();
            this.Close();
        }
        private void btncaudung_Click(object sender, EventArgs e)
        {
            btnformchinh thuyen5 = new btnformchinh();

            thuyen5.Show();
            this.Close();
        }
        private void Next_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Chúc mừng bạn đã hoàn thành!!!");
            btnformchinh form = new btnformchinh();

            form.Show();
            this.Close();
        }
        private void btncaudung_Click(object sender, EventArgs e)
        {
            MessageBox.Show("Bạn đã hoàn thành!!!");
            btnformchinh form = new btnformchinh();

            form.Show();
            this.Close();
        }