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: Robert knows it is essential that he is well behaved.

A: acceptable
****
Q: He seems intelligent to study medicine.

A: acceptable
****
Q: Is the boy who holding the plate can see the girl?

A:
acceptable
****