Question about the GetType method used by the interface

C # The Code is as follows:
Public interface iconfiginfo
{
}
Public Class A: iconfiginfo
{

}
Public Class B
{
Void BB (iconfiginfo)
{
Type T = A. GetType ();
}
}

The VB.net code is as follows:
Public interface iconfiginfo
End Interface
Public Class
Implements iconfiginfo

End Class
Public Class B
Private sub BB (byval A as iconfiginfo)
Dim t as type = A. GetType ()
End sub
End Class, please pay attention to the red part. Among them, the C # code runs normally, while VB does not. The error cause is: A. GetType ()Tip: GetType is not a member of iconfiginfo.

In the garden, Sha Jia said:
Convert a to an object first.
----
Dim t as type = ctype (A, object). GetType ()

---
This is the case .... Very depressed. Why can a. GetType () be used in C # To obtain the object type, but not in VB?