instruction: Is the next sentence syntactically and semantically acceptable?

Nora sent at the book to Peter.

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

What did you say (that) the poet had written?

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

This silver polishes itself.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

If so, I've lost $500.

response:
acceptable