instruction: Is the next sentence syntactically and semantically acceptable?

Fred must have both been singing songs and been drinking beer.

response: acceptable


instruction: Is the next sentence syntactically and semantically acceptable?

Amanda carried at the package to New York.

response: unacceptable


instruction: Is the next sentence syntactically and semantically acceptable?

The boy Bill and who I watched was vain.

response: unacceptable


instruction: Is the next sentence syntactically and semantically acceptable?

Robert knows it is essential that he is well behaved.

response:
acceptable