using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var super = new SuperClass() { A = "911" };

        var inherited = new InheritedClass(super);

        Console.WriteLine(inherited.A);

    }

}

​

public class SuperClass

{

    public object A;

​

    public SuperClass()

    {

        A = "123";

    }

​

    // you need to have this

    public SuperClass(SuperClass super)

    {

        A = super.A;

    }

}

​

public class InheritedClass : SuperClass

{

    public object B;

​

    public InheritedClass()

    {

        Init();

    }

​

    // and this

    public InheritedClass(SuperClass super): base(super)

    {

        Init();

    }

​

    private void Init()

    {

        B = "456";

    }

}