You're given a sentence and your task is to classify whether the sentence is acceptable or not. Any sentence which is grammatically correct, has a naturalistic text, is written by a native speaker and which minimizes superfluous content is acceptable, otherwise unacceptable. If the sentence is acceptable then write "acceptable", otherwise "unacceptable".

It is this hat that it is certain that he was wearing.
acceptable

Fred kicked the ball over the fence.
acceptable

Rory had eaten the muffins.

acceptable