1. Open the PPT and create a blank presentation.
2. Click [Insert]-[Graph]-[Line chart with data mark].
3. Click [OK] to get a line chart of the default style and data.
4. Enter the data for making line chart and horizontal line in the Excel table, and the line chart will be generated automatically following the data, where the horizontal line data is only one point in the figure.
5. Select the chart and click [Change chart type].
6. In the window that opens, click [Combination] on the left, and select [Line graph with data mark] for [Line chart] on the right, and [Scatter chart] for [Horizontal data], and uncheck [ Secondary axis].
7. Click [OK] to get the combined chart of line chart and scatter chart. There is no difference in appearance from the previous chart, but substantial changes have occurred.
8. Click the point of [Horizontal line data], and click [Add chart element]-[Error line]-[Other error line options].
9. In the setting window that automatically opens on the right, set the value of [Vertical Error Bar] to 0, that is, no vertical error bar is displayed.
10. Switch to [horizontal error line], [error amount] click [specified value], and enter 4 and 1 in the window that opens.
11. In this way, the error line becomes a straight line running through the drawing area.
12. Finally, beautify the chart to get the final effect.