instruction:
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".
question:
What exploded when?
answer:
acceptable


question:
I saw him leaving the main building.
answer:
acceptable


question:
Calvin did not do a back flip.
answer:

acceptable