请问我这段代码错在哪?

红色为错误地方,错误提示:
错误 1 应输入 ; C:\UTCServerC#200809231\UTCServer\Frm_main.cs 25 21 UTCServer
错误 2 应输入 ; C:\UTCServerC#200809231\UTCServer\Frm_main.cs 25 27 UTCServer
错误 3 成员修饰符“public”必须位于成员类型和名称之前 C:\UTCServerC#200809231\UTCServer\Frm_main.cs 28 9 UTCServerusing System;
using System.Net;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Net.Sockets;
using System.Data.SqlClient;
using System.Threading;
using System.IO.Ports;
using System.Diagnostics;namespace UTCServer
{
    public partial class Frm_main : Form
    {         public string strcon;         //数据库连接字符串
        //PublicClass pubclass = new PublicClass();        PublicClass pubclass = new PublicClass();
        //服务端sock端口号
        Public host As Net.IPHostEntry 
       
       
        public Frm_main()        {
            InitializeComponent();
        }        /////////////////////////////////
        //方法：加裁主窗体
        //参数：
        //功能：初始化通信参数，初始化用户、信号机列表
        //作者：吕卫民
        /////////////////////////////////
        private void Frm_main_Load(object sender, EventArgs e)
        {
            int i;//循环标志            //显示登录窗动画            Frm_logo frm1 = new Frm_logo();
            frm1.Show();            //初始化本地通信参数
            host = Dns.GetHostByName(Dns.GetHostName);       //获取本地主机的计算机名
            ip = host.AddressList(0);                        //取本地主机的IP地址
            TxtLocalIP.Text = ip.ToString;                   //将本地主机的IP地址转成字符串类型
            TxtLocalPort.Text = "4001";                      //设置本地端口号（客户端连接用）            //初始化用户列表
            LV_client.Items.Clear();                         //LV_client登录的客户端列表
            LV_client.View = View.Details;                   //设置View属性为详细资料型
            LV_client.LargeImageList = ImageList1;           //大图标由ImageList1提供
            LV_client.SmallImageList = ImageList2;           //小图标由ImageList2提供            strcon = pubclass.GetConnStr();//获取连接字符串            //初始化信号灯列表
            cross_list("广州支队");      //查询数据库，列出系统信息中所有的路口            //初始化checkbox，StatusBar
            this.RDB_COM.Checked = true; //加载窗体时为串口通信
            this.Btn_DTU_NO.Enabled = false; //未登记DTU列表
            this.RDB_TCP.Enabled = false; //TCP通信不可用
            this.StatusBar1.Panels(1).Text = "有线模式：串口";
            this.StatusBar1.Panels(2).Text = "";        }        /////////////////////////////////
        //方法：显示路口（信号机）列表
        //参数：
        //功能：从数据库中查询并显示路口（信号机）列表
        //作者：吕卫民
        /////////////////////////////////
        private void cross_list()
        {
            int i,j;
            string strSQL;
            DataSet ds1= new DataSet();
            DataSet ds2= new DataSet();
            DataSet ds3= new DataSet();
            DataSet ds4= new DataSet();            LV_cross.Columns.Clear();    //清除所有列
            LV_cross.Items.Clear();      //清除所有行            CKB_ALL.Checked = false;     //全选按钮不选            LV_cross.View = View.Details;    //设置View属性为报表型            LV_cross.LargeImageList = ImageList1;
            LV_cross.SmallImageList = ImageList2;            strSQL = "SELECT crossNum,crossName,suoshuID,DD_ID,DTU_ID,IP,Port,Addcode FROM JK_Sysrecord order by crossNum";            ds1 = pubclass.ExecuteSQL(strSQL, strcon);   //执行查询动作，将结果写入thisDataSet数据集            if (ds1.Tables[0].Rows.Count == 0)     //无任何记录
                MessageBox.Show("无路口数据！");
            else     //有记录
            {
                LV_cross.Items.Clear(); //清空                LV_cross.Columns.Add("路口编号", 90, HorizontalAlignment.Left);          //对LV_cross的列头进行初始化
                LV_cross.Columns.Add("路口名称", 160, HorizontalAlignment.Left);
                LV_cross.Columns.Add("所属大队", 130, HorizontalAlignment.Left);
                LV_cross.Columns.Add("DTU编号", 100, HorizontalAlignment.Left);
                LV_cross.Columns.Add("串口", 80, HorizontalAlignment.Left);
                LV_cross.Columns.Add("信号机IP", 140, HorizontalAlignment.Left);                ListViewItem lvi;   //定义ListView主项变量
                ListViewItem.ListViewSubItem lvsi; //定义ListView子项变量                for (i = 0; i <= thisDataSet.Tables[0].Rows.Count - 1; i++)   //遍历所有的记录
                {                    lvi = new ListViewItem();   //实例化主项
                    lvi.Text = Convert.ToString(thisDataSet.Tables[0].Rows[i]["crossNum"]);                    lvsi = new ListViewItem.ListViewSubItem();
                    lvsi.Text = Convert.ToString(thisDataSet.Tables[0].Rows[i]["crossName"]);
                    lvi.SubItems.Add(lvsi); //添加子项                    
                    //通过系统基本数据记录表JK_Sysrecord中的所属编号查到信号机被管理的等级
                    SQL = "select Bumen_name,Level_ID,PID from JK_Sysbianhao where Bianhao_ID=" & ds1.Tables(0).Rows(i).Item("suoshuID");
                    ds2 = pubclass.ExecuteSQL(SQL, strcon);
                    if (ds2.Tables[0].Rows.Count > 0)
                    {
                        if (ds2.Tables[0].Rows[0].Item["Level_ID"] = 3)          //如果是直属于大队级的则直接显示大队编号
                        {
                            LV_cross.Items(i).SubItems.Add(Trim(ds2.Tables[0].Rows[0].Item["Bumen_name"]));  //添加本行的子项
                        }
                        else if (ds2.Tables[0].Rows[0].Item["Level_ID"] >= 4)     //如果不是大队级的
                            {
                            SQL = "select Bumen_name,Level_ID,PID from JK_Sysbianhao where Bianhao_ID=" & ds2.Tables[0].Rows[0].Item["PID"];
                            ds3 = pubclass.ExecuteSQL(SQL, strcon);
                            if (ds3.Tables[0].Rows.Count > 0)
                                {
                                if (ds2.Tables[0].Rows[0].Item["Level_ID"] = 4)  //则看是否为中队级的，如果是中队级的，则显示中队所属的上级大队的名称
                                    LV_cross.Items(i).SubItems.Add(Trim(ds3.Tables[0].Rows[0].Item["Bumen_name"]));
                                
                                if (ds2.Tables[0].Rows[0].Item("Level_ID") = 5)  //如果为干线级的，则显示干级的上级中队所属的大队名称
                                    {
                                    SQL = "select Bumen_name,Level_ID from JK_Sysbianhao where Bianhao_ID=" & ds3.Tables[0].Rows[0].Item["PID"];
                                    ds4 = pubclass.ExecuteSQL(SQL, strcon);
                                    if (ds4.Tables[0].Rows.Count > 0)
                                        LV_cross.Items[i].SubItems.Add(Trim(ds4.Tables[0].Rows[0].Item["Bumen_name"]));
                                    ds4.Dispose();
                                    }
                                }
                            ds3.Dispose();
                            }
                    }
                    ds2.Dispose();
                    lvsi = new ListViewItem.ListViewSubItem();
                    lvsi.Text = Convert.ToString(thisDataSet.Tables[0].Rows[i]["Port"]);
                    lvi.SubItems.Add(lvsi);//添加子项                    lvsi = new ListViewItem.ListViewSubItem();
                    lvsi.Text = Convert.ToString(thisDataSet.Tables[0].Rows[i]["IP"]);
                    lvi.SubItems.Add(lvsi);//添加子项                    lvsi = new ListViewItem.ListViewSubItem();
                    lvsi.Text = "";
                    lvi.SubItems.Add(lvsi);//添加子项                    this.LV_cross.Items.Add(lvi);
                }
            }
            thisDataSet.Dispose();   //释放数据集资源
        }    }
}