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]: Calvin had been eating.
[A]: acceptable


[Q]: I threw Mary the ball, but she was looking at the birds flying overhead and didn't even notice.
[A]: acceptable


[Q]: the book of poems from Blackwell by Robert Burns with a red cover takes a very long time to read.
[A]:
acceptable