using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;namespace Demo{    public abstract class MyBase    {    }    internal class MyClass : MyBase    {    }    public interface IMyBaseInterface    {    }    internal interface IMyBaseInterface2    {    }    internal interface IMyInterface : IMyBaseInterface,IMyBaseInterface2    {    }    internal sealed class MyComplexClass : MyClass,IMyInterface    {    }    class Program    {               static void Main(string[] args)        {            MyComplexClass myObj = new MyComplexClass();            Console.WriteLine(myObj.ToString());            Console.ReadKey();        }    }}

一个namespace可以定义多种类与接口，有意思。