The Search and Replace dialog box will pop up. Click more buttons in the dialog box. In the pop-up dialog box, move the cursor to the blank dialog box behind the search content, click the special format button, and click any letter option from the pop-up menu options. Through the previous operation, a symbol will appear in the dialog box behind the search content. Click the Read Highlights button, select all highlighting options from the pop-up menu options, and then close the dialog box.

Go back to the document and find all the English letters in the article and highlight them.