图片：缺少 alt 属性

Images that are missing an alt attribute all together. Click the address (URL) of the image and then the 'Image Details' tab in the lower window pane to view which pages have the image on, and are missing alt attributes. All images should contain an alt attribute with descriptive text, or blank when it's a decorative image.

How to fix: Include alt attributes with 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.