1. Web page design problem: There may be a problem with the design of the Web page, which causes the drop-down menu not to be displayed normally. In this case, it is recommended that you try to open the webpage on other browsers or devices to see if the same problem exists.

2. Network connection problem: If your network connection is unstable or slow, the drop-down menu may not be displayed normally. It is recommended that you check whether the network connection is normal and try to refresh or reload the page.

3. Personal permissions: If the webpage is dedicated to the enterprise, you may need to log in or have specific permissions to access and use the drop-down menu. It is recommended that you log in according to the webpage prompts or contact the relevant person in charge to solve the permission problem. You can also contact the relevant departments or technical support personnel of Guangdong Intelligent Food and Drug Administration for further help and solutions.