instruction: Is the next sentence syntactically and semantically acceptable?

You must pick any flower in this bed.

response: unacceptable

instruction: Is the next sentence syntactically and semantically acceptable?

About 20 liters of acid was poured into the beaker.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

For John to love Mary would be doubtful.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Medea tended to appear to be evil.

response:
acceptable