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".

[EX Q]: Robert knows it is essential that he is well behaved.
[EX A]: acceptable

[EX Q]: The boy's loud playing of the piano drove everyone crazy.
[EX A]: acceptable

[EX Q]: It seems to be easy to fool Ben.
[EX A]:
acceptable