1. Determine the coordinate axis: select the appropriate scale and coordinate system. Usually, the vertical axis is oxygen concentration and the horizontal axis is time.

2. Data collection: According to the experiment or theoretical calculation, the data of SO oxygen concentration changing with time is obtained.

3. Draw a point chart: the SO oxygen concentration at each time point is represented by points, which are connected in time sequence. In this way, a curve can be obtained to show the change of SO oxygen concentration with time.

4. Add marks: mark important points, areas or features on the curve, such as the highest point, lowest point and inflection point of the curve.

5. Add a title and description: Add a title and description to the chart to help the observer understand the content of the chart.