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Shift cells right
Insert a cell and move all other cells in that row to the right.
NOTE Word does not insert a new column. This may result in a row that has more cells than the other rows.
Shift cells down
Insert a cell and move the existing cells down one row. A new row is added at the bottom of the table.
Insert entire row
Insert a row above the cell that you clicked in.
Insert entire column
Insert a column to the left of the cell that you clicked in.