代码

using System;
using System.Collections.Generic;
using System.Linq;namespace Linq
{class Program{static void Main(string[] args){Console.WriteLine("Hello World!");var query = from r in Formulal.GetChampions() select r;foreach(int i in query){Console.WriteLine(i);}Console.ReadLine();}}static class Formulal{private static List<int> s_racers;private static List<int> InitializeRacers() => new List<int> { 1, 2, 3, 4, };public static IList<int> GetChampions() => s_racers ?? (s_racers = InitializeRacers());}
}

运行结果

Hello World!
1
2
3
4