The advanced editing function of inserting formulas requires the editor of Adobe, the creator of pdf files, to edit PDF files. Generally, two softwares are used: 1. Adobe Acrobat (not Adobe Reader) 2. Foxit PDF Editor now introduces the method of editing a PDF file with Adobe Acrobat software: first, you open the PDF file, click Tools-Advanced Editing Tools -Touch Up Text Tool (T) in turn, and then click where you need to edit with the mouse, and a rectangular border will appear. In this box, you put. If you need to change the font, size and color, you can select Chinese characters and click with the right mouse button. A dialog box will pop up, click "Properties", and then select what you want in the "Font Size" column in the "Text" column of the pop-up dialog box. Using Foxit PDF editor software to modify PDF files is not very convenient and requires high skills (but it is very useful when filling out PDF forms), so I won't introduce its usage here.