Problem: Produce a sentence that would be considered grammatically unacceptable

Answer: Who does Phineas know a girl who is behind?

Problem: Produce a sentence that would be considered grammatically acceptable

Answer: An old woman lodged at Mrs. Parker's.

Problem: Produce a sentence that would be considered grammatically unacceptable

Answer:
At 4 p.m. I saw John lecturing to anyone who was near him.