Aggregate string value

using System;/*j  a  va2  s.  c  o m*/
using System.Collections.Generic;
using System.Linq;
using System.Text;

class Program
{
    static void Main(string[] args)
    {
        string[] curries = { "abc", "abcd", "ab" };
        Console.WriteLine(curries.Aggregate((a, b) => a + " " + b));
    }
}

using System;/* j  a  v a 2 s . c  om*/
using System.Collections.Generic;
using System.Linq;

class Program
{
    private static string ReverseString(string sentence)
    {
        List<string> words = new List<string>(sentence.Split(' ').ToList());

        return words.Aggregate((a, b) => b + " " + a);            
    }

    static void Main(string[] args)
    {
        string sentence = "this is a test";
        string result = ReverseString(sentence);
        Console.WriteLine(result);
    }        
}