class Program
    {
        static void Main(string[] args)
        {
            List<Test> tList = new List<Test>();
            tList.Add(new Test(){
                time=DateTime.Parse("2010-11-30"),
                content="这是内容1"
            });
            tList.Add(new Test()
            {
                time = DateTime.Parse("2010-11-30"),
                content = "这是内容2"
            });
            tList.Add(new Test()
            {
                time = DateTime.Parse("2010-11-30"),
                content = "这是内容3"
            });
            tList.Add(new Test()
            {
                time = DateTime.Parse("2010-11-29"),
                content = "这是内容4"
            });
            tList.Add(new Test()
            {
                time = DateTime.Parse("2010-11-29"),
                content = "这是内容5"
            });
            


            List<Test> temp = tList.Distinct(new Comparer()).ToList<Test>();
            foreach (var o in temp)
            {
                foreach (var p in tList)
                {
                    if (p.time == o.time&&p.content!=o.content)
                    {
                        o.content += ","+p.content;
                    }
                }
            }

            foreach (var o in temp)
            {
                Console.WriteLine(o.time+"   "+o.content);
            }

            
            Console.Read();
        }
    }

    public class Comparer : IEqualityComparer<Test>
    {
        #region IEqualityComparer<Test> Members

        public bool Equals(Test x, Test y)
        {
            if (x == null || y == null)
                return false;
            return x.time == y.time;
        }

        public int GetHashCode(Test obj)
        {
            return obj.ToString().GetHashCode();
        }

        #endregion
    }

    public class Test
    {
        public DateTime time { get; set; }

        public string content { get; set; }
    }