找代理服务手工验证是一个很繁琐的工作，本代码使用C#抓取代理地址列表,通过 www.cnproxy.com等网站， 并自动完成对可用代理服务器验证功能-Looking for proxy service manual verification is a very tedious work, the code uses the C# proxy address list to crawl through www.cnproxy.com such sites, and automatical