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: What do you think he is doing now?

SOLUTION: acceptable

PROBLEM: I bought the parrot in the store.

SOLUTION: acceptable

PROBLEM: Which book by his father did he read?

SOLUTION:
acceptable