以下程序只能读取dxf文件中多段线（二维）的一个点的坐标（左端点），但多段线有三个点，哪位大神能帮忙改改。

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            string fn = @"1.dxf";
            ReadDxf rd = new ReadDxf(fn);
            ArrayList abc = new ArrayList();
            abc=rd.ReadPolyline(@"0");

            double[,] ps=new double[abc.Count,2];
            for (int i = 0; i < abc.Count; i++)
            {
                double[] ds = new double[2];
                ds = (double[])abc[i];
                ps[i, 0] = ds[0]; ps[i, 1] = ds[1];


                WriteToFile wtf = new WriteToFile(@"1.txt");
                string[] str = new string[2];
                str[0] = ps[0, 0].ToString("F3");
                str[1] = ps[0, 1].ToString("F3");
                wtf.WriteStringByLine(str);
                wtf.Close();
            }

            

                     
        }
    }
}
（ReadDxf为引用的类）