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]: They can sing.
[EX A]: acceptable

[EX Q]: Who do you think that Mary said that John likes?
[EX A]: acceptable

[EX Q]: I know a man who John is taller than is.
[EX A]:
unacceptable