练习：WinForm 三级联动（中国行政区划）

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

namespace 三级联动.Model
{
    class China
    {
        private string code;

        public string Code
        {
            get { return code; }
            set { code = value; }
        }
        private string name;

        public string Name
        {
            get { return name; }
            set { name = value; }
        }
        private string parentcode;

        public string Parentcode
        {
            get { return parentcode; }
            set { parentcode = value; }
        }
    }
}

实体类