重复列表< T> .Add(T项目)项目

为什么aFooList包含最后一个项目的五个副本，而不是我插入的五个项目?

Why does aFooList contain five copies of the last item, instead of the five items I inserted?

预期输出:01234

实际输出:44444

using System;
using System.Collections.Generic;

namespace myTestConsole {
    public class foo {
        public int bar;
    }

    class Program {
        static void Main(string[] args) {
            foo aFoo = new foo(); // Make a foo
            List<foo> aFooList = new List<foo>(); // Make a foo list

            for (int i = 0; i<5; i++) { 
                aFoo.bar = i;
                aFooList.Add(aFoo);
            }

            for (int i = 0; i<5; i++) {
                Console.Write(aFooList[i].bar);
            }
        }
    }
}