C# 复制遍历文件夹下所有文件夹内指定文件 ，到指定位置

using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace UserWAVE
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void btn_原文件_Click(object sender, EventArgs e)
        {
            FolderBrowserDialog dialog = new FolderBrowserDialog();
            dialog.Description = "请选择文件路径";
            //dialog.RootFolder = Environment.SpecialFolder.Programs;
            if (dialog.ShowDialog() == DialogResult.OK)
            {
              textBox1.Text = dialog.SelectedPath;
            }
        }
        private void btn_目标文件_Click(object sender, EventArgs e)
        {
            FolderBrowserDialog dialog = new FolderBrowserDialog();
            dialog.Description = "请选择文件路径";
            //dialog.RootFolder = Environment.SpecialFolder.Programs;
            if (dialog.ShowDialog() == DialogResult.OK)
            {
                textBox2.Text = dialog.SelectedPath;
            }
        }
        private void btn_OK_Click(object sender, EventArgs e)
        {
            GetDirectory(textBox1.Text);
           var a= directorysList;
            // CopyFolder2(textBox1.Text, textBox1.Text);
            for (int i = 0; i < directorysList.Count; i+