http://msdn.microsoft.com/zh-cn/library/bb397926.aspx
http://kb.cnblogs.com/zt/linq/
http://www.cnblogs.com/foundation/archive/2009/01/05/1369346.html
http://www.soaspx.com/dotnet/csharp/csharp_20101230_6999.html
原文：http://www.cnblogs.com/haiy/p/4146102.html