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: It tries to be warm in September.

A: unacceptable
****
Q: Ellen conferred with Helen.

A: acceptable
****
Q: Experts all agree that dreams cause great anxiety and stress are called nightmares.

A:
acceptable
****