先添加一个类

using System;

using static System.Console;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace 练习1

{

public abstract class Animal

{

protected string name;

public string Name

{

get { return name; }

set { name = value; }

}

public Animal()

{

name = "没有名字的动物";

}

public Animal(string newName)

{

name = newName;

}

public void Feed() => WriteLine($"{name}已被馈赠");

}

}