instruction: Is the next sentence syntactically and semantically acceptable?

It was roses that the gardener planted in the garden.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Every cat doesn't like mice.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Robert knows it is essential that he is well behaved.

response: acceptable

instruction: Is the next sentence syntactically and semantically acceptable?

Gilgamesh is in the dungeon.

response:
acceptable