instruction: Is the next sentence syntactically and semantically acceptable?

Anne and Cathy met.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

The student knowing the answers.

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

he had been reading the article.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Ellen told Helen.

response:
acceptable