winform中如何使用确认对话框

        private void btnExit_Click(object sender, EventArgs e)
        {
            MessageBoxButtons mess = MessageBoxButtons.OKCancel;
            DialogResult dr = MessageBox.Show("有未处理的数据，确认退出系统？", "提示", mess);
            if (dr == DialogResult.OK)
            {
                Environment.Exit(0);
            }
        }