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".

[Q]: Willy is taller than that Bill is is generally believed.
[A]: unacceptable


[Q]: When did you get back and what did you bring me?
[A]: acceptable


[Q]: John hummed, and Mary sang, at equal volumes.
[A]:
acceptable