问题：

[多选] Which three demonstrate an “is a” relationship？（） 

A .  public class X { }  public class Y extends X { }
B .  public interface Shape { }  public interface Rectangle extends Shape{ }
C .  public interface Color { }  public class Shape { private Color color； }
D .  public interface Species { }  public class Animal { private Species species； }
E .  public class Person { }  public class Employee {  public Employee（Person person） { }
F .  interface Component { }  class Container implements Component {  private Component[] children； }