c# 委托访问listbox多线程操作

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
using System.Threading;


namespace test
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        delegate void SendToParent(string txt);

       // public delegate string SendToParent();
        mysqlConnect conn = new mysqlConnect();
        DataTable dt = new DataTable();
        time tm = new time();
        private void Form1_Load(object sender, EventArgs e)
        {
           
            conn.getConnection();