问如何解压所有的.Zip文件从文件夹使用C# 4.0，而不使用任何OpenSource动态链接库？

EN

using System;
using System.IO;
using System.IO.Compression;

namespace ConsoleApplication
{
    class Program
    {
        static void Main(string[] args)
        {
            string startPath = @"c:\example\start";
            string zipPath = @"c:\example\result.zip";
            string extractPath = @"c:\example\extract";

            ZipFile.CreateFromDirectory(startPath, zipPath);

            ZipFile.ExtractToDirectory(zipPath, extractPath);
        }
    }
}

public static void UnZip(string zipFile, string folderPath)
{
    if (!File.Exists(zipFile))
        throw new FileNotFoundException();

    if (!Directory.Exists(folderPath))
        Directory.CreateDirectory(folderPath);

    Shell32.Shell objShell = new Shell32.Shell();
    Shell32.Folder destinationFolder = objShell.NameSpace(folderPath);
    Shell32.Folder sourceFile = objShell.NameSpace(zipFile);

    foreach (var file in sourceFile.Items())
    {
        destinationFolder.CopyHere(file, 4 | 16);
    }
}