图片：alt 文本为空

Images that have an alt attribute, but are missing alt text. Click the address of the image and then the 'Image Details' tab in the lower window pane to view which pages have the image on them, and are missing alt text. Images should have descriptive alternative text about its purpose, which helps the blind and visually impaired, and the search engines understand it and its relevance to the web page.

How to fix: Include descriptive alt text for images to help users and the search engines understand them better. Where possible, decorative images should be provided using CSS background images or alternatively a null (empty) alt text should be provided (alt="") so that they can be ignored by assistive technologies, such as screen readers.