Combine tool is missing in Acrobat

Hi Xinli29335317von9,

Thank you for reaching out, and sorry about the delay in response.

Please let's know if the option is still unavailable on the desktop application.

If yes, try reinstalling the application using the following steps: 

- Remove the application and run the cleaner tool (https://www.adobe.com/devnet-docs/acrobatetk/tools/Labs/cleaner.html).
- Reboot the machine
- Install Adobe Acrobat Pro from the following page: https://helpx.adobe.com/acrobat/kb/acrobat-dc-downloads.html.

Let us know if the issue persists.

Thanks,

Meenakshi