u can, but then u won't be F1
there is also some debate on whether or not you can extend your F1 also since you already filed 485.
While it is possible to maintain your F1 non-immigrant status after 485 filing, it is generally believed that you can't extend it after it has expired. And if you use any of the benefits of 485 filing, such as EAD/AP, then you definitely will loose your F1 status.