If currently no cell is selected, a new column will be inserted at the right border of the table. If currently cells are selected, as many new columns as the selection has will be inserted right of the selection.
如果当前未选定任何单元格，则会在表格右边框处加入一个新列。如果当前有单元格被选定，则会在选定区域右侧插入与选定列相同数量的新列。