using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        IList<string> strList = new List<string>(){ "1", "1", "Five", "1" };

​

        var newList = strList.TakeWhile(s => s == "1");

        foreach(var str in newList)

            Console.WriteLine(str);

        Console.WriteLine("-------");

        var newList2 = strList.Where(s => s == "1");

        foreach(var str in newList2)

            Console.WriteLine(str);

    }

}