If you can add "by zombies," you probably have a passive voice sentence that you should rewrite with those "zombies" front and center.
Here's an example:
❌ The dogs were walked [by zombies].
✅ Zombies walked the dogs.
Here's a more real-life example:
❌ The report was sent Friday [by accounting].
✅ Accounting sent the report Friday.
(And I in no way mean to imply that accounting is full of zombies! 🤣)