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".

The captain sank the boat.
acceptable

Have in our class the kids arrived safely?
unacceptable

I believed these students all to like John.

acceptable