我需要有关“此”关键字和继承的帮助

abstract class BaseClass
{
    public virtual void Accept(IVisitor visitor)
    {
        visitor.Visit(this);
    }
}

class DerivedClass: BaseClass
{
}

interface IVisitor
{
    void Visit(BaseClass baseEntity);
    void Visit(DerivedClass derivedEntity);
}

class Visitor : IVisitor
{
    public void Visit(DerivedClass derivedEntity)
    {
        Debug.WriteLine("Derived Entity visited");
    }

    public void Visit(BaseClass baseEntity)
    {
        Debug.WriteLine("Base Entity visited");
    }
}

经过上述脱节

class Program
{
    static void Main(string[] args)
    {
        DerivedClass derived = new DerivedClass();
        Visitor visitor = new Visitor();
        derived.Accept(visitor);
    }
}

产生

"Base Entity visited"

但是我希望它能产生

"Derived Entity visited"

• 谁能解释为什么？
• 我应该怎么做才能产生“拜访的派生实体”？我不想覆盖“接受”功能。