reference C:\Windows\Microsoft.NET\Framework\v2.0.50727\System.dll
System.Console: WriteLine
System.Net.WebClient: DownloadStringAsync, DownloadStringCompleted, DownloadString, DownloadStringCompletedEventHandler
System.Net.DownloadStringCompletedEventArgs: Result, UserState
System.Uri
System.Threading.Thread: Sleep
System.Threading.ParameterizedThreadStart: Invoke
System.Object: ToString