using System;

using HtmlAgilityPack;

using Fizzler.Systems.HtmlAgilityPack;

​

public class Program

{

    public static void Main()

    {

        var output = @"

                      <table>

                      <tbody

                      <tr class =""thead"">

                        <th> 1h</th>

                        <th> 2h</th>

                        <th> 3h</th>

                        <th> 4h</th>

                        <th> 5h</th>

                      </tr>

                      <tr class=""tdata"">

                        <td> 1cell</td>

                        <td> 2cell</td>

                        <td> 3cell</td>

                        <td> 4cell</td>

                        <td> 5cell</td>

                      </tr>

                      <tr class=""tdata"">

                        <td> 1cell</td>

                        <td> 2cell</td>

                        <td> 3cell</td>

                        <td> 4cell</td>

                        <td> 5cell</td>

                      </tr>

                      </tbody>

                    </table>";

        var doc = new HtmlDocument();

        doc.LoadHtml(output);

        var nodes = doc.DocumentNode.QuerySelectorAll("th:nth-child(1), th:nth-child(3), th:nth-child(4), td:nth-child(1), td:nth-child(3),  td:nth-child(4)"); 

        foreach (HtmlNode node in nodes)

        {

            Console.WriteLine(node.InnerText);

        }

    }

}