如何在一个类中同时使用抽象和虚拟方法？

public abstract class Animal
{
    public abstract void MakeSound();

    public virtual void Eat()
    {
        Console.WriteLine("Animal is eating.");
    }
}

public class Dog : Animal
{
    public override void MakeSound()
    {
        Console.WriteLine("Dog is barking.");
    }

    public override void Eat()
    {
        Console.WriteLine("Dog is eating.");
    }
}

public class Cat : Animal
{
    public override void MakeSound()
    {
        Console.WriteLine("Cat is meowing.");
    }

    public override void Eat()
    {
        Console.WriteLine("Cat is eating.");
    }
}