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