... (ALT+F11), chọn Insert -> Module rồi gõ vào (ho c copy) các dòng sau đây : Const Slide_Number = 1Const Thoi_Gian = 10Sub Dem_ Nguoc( )Dim Ngung As Boolean, Dem As Integer, Gio_Cu As Single, Gio_Moi ... Gio_Moi > Gio_Cu Then Dem = Dem - 1Gio_Cu = Gio_MoiActivePresentation.Slides(Slide_Number).Shapes(N). TextFrame.TextRange.Text = Format (Dem, "00")If Dem = 0 Then Ngung = TrueEnd ... False Dem = Thoi_GianGio_Cu = Int(Timer)N = ActivePresentation.Slides(Slide_Number).Shapes.Cou ntActivePresentation.Slides(Slide_Number).Shapes(N). TextFrame.TextRange.Text = Format (Dem, "00")Do...