Task execution

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Net.Http;

namespace testAsync
{
    class Program
    {
        static Task<HttpResponseMessage> globalTask;

        static void Main(string[] args)
        {
            CallAsync();
            Console.WriteLine(globalTask.IsCompleted); // False

            globalTask = null; // Not really necessary
            CallAsync();
            Task.Delay(500).Wait();
            Console.WriteLine(globalTask.IsCompleted); // True

            Console.ReadLine();
        }

        static void CallAsync()
        {
            using (HttpClient client = new HttpClient())
            {
                globalTask = client.GetAsync("http://www.google.com");
            }
        }
    }
}