instruction: Is the next sentence syntactically and semantically acceptable?

Himself likes John.

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Who is Ann going to send a picture to her teacher of, as soon as she gets home?

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

John thinks that Mary left.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

There are three Davids in my class.

response:
acceptable