YOU SAID:

There wasn’t a rat in the sky (no rats allowed in the sky)

INTO JAPANESE

空にはネズミがいなかった(空にはネズミは入ってない)

BACK INTO ENGLISH

There were no rats in the sky (there were no rats in the sky)

INTO JAPANESE

空にはネズミはいなかった(空にはネズミはいなかった)

BACK INTO ENGLISH

There were no rats in the sky (there were no rats in the sky)