以下为引用的内容：

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

namespace CompTax
{
    public class CompTax
    {
        private double Taxp;
        private double Minincome;
        private static double Disc=2000;
        private CompTax NextCompTax;
        public CompTax(double Minincome, double Taxp)
        {
            this.Minincome = Minincome;
            this.Taxp = Taxp;
            NextCompTax = null;
        }
        public double Comp(double income)
        {

            if(income > Minincome && (NextCompTax==null|| income< NextCompTax.Minincome))
            {
                return (income - Disc) * Taxp;
            }
            else
            {
                return NextCompTax.Comp(income);
            }
        }

        public static CompTax GetInstance()
        {
            CompTax[] cp ={
                             new CompTax(2000,0.05),
                             new CompTax(2500,0.1),
                             new CompTax(4000,0.15),
                             new CompTax(7000,0.2),
                             new CompTax(22000,0.25),
                             new CompTax(42000,0.3),
                             new CompTax(62000,0.35),
                             new CompTax(82000,0.4),
                             new CompTax(102000,0.45)
                         };
            CompTax ct=null;
            for (int i = 0; i < cp.Length-1; i++)
            {
                if (i == 0)
                    ct = cp[i];
                cp[i].NextCompTax = cp[i + 1];
            }
            return ct;
        }
    }
}

以下为引用的内容：

        private void button1_Click(object sender, EventArgs e)
        {
            textBox2.Text = CompTax.GetInstance().Comp(double.Parse(textBox1.Text)).ToString();
        }