1：运行结果

代码如下：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

namespace Txst2_1

{

class Animal

{

private Boolean m_sex;

private int m_age;

public bool Sex

{

get { return m_sex; }

set { m_sex = false; }

}

public int Age

{

get { return m_age; }

set { m_age = value; }

}

public virtual string Introduce()

{

if (Sex == true)

return "This is a male Animal";

else

return "This is a female Animal";

}

}

class Dog:Animal

{

public Dog()

{

Sex = true;

}

public override string Introduce()

{

if (Sex == true)

return "This is a male Dog";

else

return "This is a female Dog";

}

}

class Cat:Animal

{

public override string Introduce()

{

if (Sex == true)

return "This is a male Cat";

else

return "This is a female Cat";

}

}

class Program

{

static void Main(string[] args)

{

Animal ani = new Animal();

Console.WriteLine(ani.Introduce());

Animal dog = new Dog();

Console.WriteLine(dog.Introduce());

Animal cat = new Cat();

Console.WriteLine(cat.Introduce());

Console.Read();

}

}

}