using static System.Console;

using System.Net;

using System.IO;

using System.Collections.Generic;

public class Program {

    public static void Main() {

        var paginas = BaixarTudo(new List<string>{"http://google.com", "http://yahoo.com"});

        foreach(var item in paginas) {

            WriteLine(item);

        }

    }

    public static List<string> BaixarTudo(List<string> urls) {

        var clients = new List<string>(urls.Count);

        foreach(var url in urls) {

            var client = new WebClient();

            client.Headers.Add("user-agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");

            using(var data = client.OpenRead(url)) {

                using (var reader = new StreamReader(data)) {

                    clients.Add(reader.ReadToEnd());

                }

            }

        }

        return clients;

    }

}

​

//https://pt.stackoverflow.com/q/47315/101