TASK DEFINITION: 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".
PROBLEM: He sees often Mary.

SOLUTION: unacceptable

PROBLEM: In the book, he talks about his ups and downs at school.

SOLUTION: acceptable

PROBLEM: Did that he played the piano surprise you?

SOLUTION:
unacceptable