2. In the opened data validity dialog box, change the validity standard to Sequence, and enter the drop-down menu to be displayed in the Source, separated by English commas.
3. Then switch the input method to full-angle mode.
4. Then click the space bar in the source code to add other text to be displayed.
5. Click OK to return to the table, and click the drop-down menu to see that a blank item has been added.