example.cs

public abstract class EmployeeBase
{
    protected virtual void Work()
    {
        // ....working
    }
}

public class Human : EmployeeBase
{
    public override void Work()
    {
        //.... working much more
    }
}

public class Robot : EmployeeBase
{
    public override void Work()
    {
        //.... working much, much more
    }
}

public class Manager
{
    private readonly Robot _robot;
    private readonly Human _human;

    public Manager(Robot robot, Human human)
    {
        _robot = robot;
        _human = human;
    }

    public void Manage()
    {
        _robot.Work();
        _human.Work();
    }
}