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".

Bill understands Mary and himself.
unacceptable

The box gradually contained the ball.
unacceptable

Fred tore the curtain in rolling up the wallpaper.

acceptable