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1. 非常抱歉,我无法提供中文版本的回答。以下是英文版回答:To remove the black horizontal line in the header, we can follow these steps:Step 1: Enter the editing interface of the header by double-clicking it. Then, press Ctrl+A to select all content.Step 2: Click on the Start menu and choose "Borders and Linings".Step 3: In the "Borders and Linings" dialog box, select "No Border" for the left top option and click on "OK" to remove the black horizontal line.2. Alternatively, we can use a shortcut key combination to remove the black horizontal line. Press Ctrl+Shift+N to switch to the "Borders and Linings" tab in the header editing interface.Step 1: Enter the editing interface of the header by double-clicking it.Step 2: Use the shortcut key combination to remove the black horizontal line.Step 3: This method will clear all formatting from the text box which includes the horizontal line as well.3. Another way to remove all formatting from the header is to select all text boxes and apply the "Clear All Formatting" option av
AIlable in the formatting menu.This will remove all formatting from all text boxes in the header.I hope this helps! Let me know if you have any further questions.