var encoded = ""'&<>¡¢£¤" +

              "¥¦§¨©ª«¬­®" +

              "¯°±²³´µ¶·" +

              "¸¹º»¼½¾¿" +

              "×÷ÀÁÂÃÄÅ" +

              "ÆÇÈÉÊËÌÍ" +

              "ÎÏÐÑÒÓÔÕ" +

              "ÖØÙÚÛÜÝÞ" +

              "ßàáâãäåæ" +

              "çèéêëìíî" +

              "ïðñòóôõö" +

              "øùúûüýþÿ";

var expected = "\"'&<>¡¢£¤¥¦§¨©ª«¬­®¯°±²³´µ¶·¸¹º»¼½¾¿×÷ÀÁÂÃÄÅÆÇÈÉÊËÌÍÎÏÐÑÒÓ" +

                "ÔÕÖØÙÚÛÜÝÞßàáâãäåæçèéêëìíîïðñòóôõöøùúûüýþÿ";

Console.WriteLine(System.Net.WebUtility.HtmlDecode(encoded) == expected);//解码