Classes.cs

void Main()
{
	var a = new A();
	var b = new B();
	
	a.One();
	a.Two();
	
	b.One();
	b.Two();
	
	var bAsA = (A)b;
	
	bAsA.One();
	bAsA.Two();
}

class A
{
	public virtual void One()
	{
		Console.WriteLine("Method One in class A");
	}
	
	public void Two()
	{
		Console.WriteLine("Method Two in class A");
	}
}

class B : A
{
	public override void One()
	{
		Console.WriteLine("Method One in class B");
	}
	
	public new void Two()
	{
		Console.WriteLine("Method Two in class B");
	}
}

Result.txt

Method One in class A
Method Two in class A
Method One in class B
Method Two in class B
Method One in class B
Method Two in class A