gistfile1.vb

Module Module1

    Sub Main()
        Dim s = New subclass
        s.test()
        Console.ReadLine()
    End Sub

    Public Interface IInterface
        Sub test()
    End Interface

    Public MustInherit Class baseclass
        Public Sub test()
            Console.WriteLine("baseclass")
        End Sub
    End Class

    Public Class subclass
        Inherits baseclass
        Implements IInterface
        
        Public Sub test1() Implements IInterface.test

        End Sub

    End Class

End Module