如何在电子表格中打开XML电子表格“不折叠”单元格?

I'm working with xslx Excel file on the server side in C#. In a spreadsheet, say there are 15 columns (cells) total. In the rows of cells, some values are missing. So the first row is my header will properly have the 15 cells. But my data rows, some cells might have empty values, so Open XML has a "jagged" set of cells values. Row 1 will have the full 15 cells, Row 2 might have 13 cells since two of the values are empty. What! How do I map this data properly? It basically shifts everything to the left and my cell values are wrong. What am I missing? It seems like they are being "collapsed" in Open XML terminology.I'm working with xslx Excel file on the server