Can I prevent an inherited virtual method from being overridden in subclasses?

class A
{
    public virtual void Render()
    {
    }
}
class B : A
{
    public override void Render()
    {
        // Prepare the object for rendering
        SpecialRender();
        // Do some cleanup
    }

    protected virtual void SpecialRender()
    {
    }
}
class C : B
{
    protected override void SpecialRender()
    {
        // Do some cool stuff
    }
}

A obj = new C();
obj.Render();       // calls B.Render -> c.SpecialRender

public sealed override void Render()
{
    // Prepare the object for rendering
    SpecialRender();
    // Do some cleanup
}

class B : A
{
    public sealed override void Render()
    {
        // Prepare the object for rendering
        SpecialRender();
        // Do some cleanup
    }

    protected virtual void SpecialRender()
    {
    }
}

class A
{
	public virtual void Render()
	{
	}
}
class B : A
{
	public override void Render()
	{
		// Prepare the object for rendering
		SpecialRender();
		// Do some cleanup
	}
	protected virtual void SpecialRender()
	{
	}
}
class B2 : B
{
	public new void Render()
	{
	}
}
class C : B2
{
	protected override void SpecialRender()
	{
	}
	//public override void Render() // compiler error
	//{
	//}
}

protected override sealed void Render() { ... }

class B : A
{
  protected sealed override void SpecialRender()
  {
    // do stuff
  }
}

class C : B
  protected override void SpecialRender()
  {
    // not valid
  }
}