i3.cs

public interface IAnimal {
  void Eat();
  void Drink();
  void Sleep();
}
public interface IBird {
  void Fly();
}
public interface IFish {
  void Swim();
}

// Các class chỉ cần kế thừa những interface có chúc năng chúng cần
public class Dog : IAnimal {
  public void Eat() {}
  public void Drink() {}
  public void Sleep() {}
}
public class FlappyBird: IAnimal, IBird {
  public void Eat() {}
  public void Drink() {}
  public void Sleep() {}
  public void Fly() {}
}
public class FormosaFish: IAnimal, IBird {
  public void Eat() {}
  public void Drink() {}
  public void Sleep() {}
  public void Swim() {}
}