instruction: Is the next sentence syntactically and semantically acceptable?

Yes, she did.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Pigs love truffles.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

I thought she is pregnant

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

It is believed to be obvious by everyone that Fred is crazy.

response:
acceptable