To undo your last action, click the Undo button on the Standard toolbar. Click it again to undo the previous action. To repeat an action, click the Redo button.

• 单击“常用”工具栏中的“撤消”按钮，可以撤消上一步操作，反复单击该按钮，可以逐步撤消以前的各项操作。要重复某一操作，可以单击“重复”按钮。