Private Sub Combo1_Click()
    If Combo1.List(Combo1.ListIndex) = "a" Then
        Picture1.Picture = LoadPicture("c:\a.jpg")
    ElseIf Combo1.List(Combo1.ListIndex) = "b" Then
        Picture1.Picture = LoadPicture("c:\b.jpg")
     Else
        Picture1.Picture = Nothing
    End If
 
End Sub