static void Main(string[] args)
        {
            A _a = new A();
            _a.CallHelloB();

            C _c = new C();
            _a.CallHelloB();
        }
    }

    public class A: ParentObject
    {
        public void CallHelloB()
        {
            B _b = new B (this);
            _b.HelloB();
            Console.WriteLine("End CallHelloB From Class A");
        }
    }

    public class B: ParentObject
    {
        public B(ParentObject o)
        {
            if (!(o is A))
            {
                Console.Write("Wrong Caller");
            }
        }
        public void HelloB()
        {
            Console.WriteLine("Hello B");
        }
    }

    public class C
    {
        public void CallHelloB()
        {
            B _b = new B(new A());
            _b.HelloB();
            Console.WriteLine("End CallHelloB From Class C");
        }
    }

    public class ParentObject { }

using System;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            B _b = new B();
            _b.Test();
            Console.Read();
            try
            {

                C _c = new C();
                _c.Test();
            }
            catch(Exception e)
            {
                Console.WriteLine(e.Message);
            }
            Console.ReadLine();
            Console.ReadLine();
        }
    }

    public class ParentObject { }
    interface ICallHelloB
    {
        void CallHelloB();
    }
    /// <summary>
    /// 实现ICallHelloB接口 并且只有一个带参数的构造函数
    /// </summary>
    public class A : ICallHelloB
    {
        /// <summary>
        /// 传入当前对象this
        /// 程序自动判断当前类型能否创建对象
        /// </summary>
        /// <param name="o">传入this</param>
        public A(object o)
        {
            //表示只接受ParentObject类或其派生类的对象
            if (!(o is ParentObject))
            {
                throw new Exception("Wrong Caller");
            }
        }

        public void CallHelloB()
        {
            Console.WriteLine("End CallHelloB From Class A");
        }
    }
    /// <summary>
    /// 这个类继承ParentObject实现可实例化A类以及调用它的函数
    /// </summary>
    public class B: ParentObject
    {
        public void Test()
        {
            A _a = new A(this);
            _a.CallHelloB();
        }
    }
    /// <summary>
    /// 该类不继承ParentObject类所以无法实例化A类并抛出异常
    /// </summary>
    public class C
    {
        public void Test()
        {
            A _a = new A(this);//这里运行时抛出异常
        }
    }
}

    public class C
    {
        public void Test()
        {
            A _a = new A(new ParentObject());
        }
    }