谁能用例子演示下VB实现多态？

[x_x_j]

谁能用例子演示下VB实现多态？最好帮我分析分析多态和函数重载，谢了

[TechnoFantasy]

在工程中创建3个Class Module，名字分别为：Animal、Cat、Dog：

Animal是接口：
Sub Cry()

End Sub

Cat和Dog类是实现：

Implements Animal

Private Sub Animal_Cry()
MsgBox "miao miao"
End Sub


Implements Animal


Private Sub Animal_Cry()
MsgBox "wang wang"
End Sub


然后调用的代码如下：
Private Sub Command1_Click()
Dim a1 As Animal
Dim a2 As Animal

Set a1 = New Dog
Set a2 = New Cat

a1.Cry
a2.Cry
End Sub

[x_x_j]

牛人讲话就是容易懂，谢啦！