YOU SAID:
There once was a cat that ate a rat.
INTO JAPANESE
かつてネズミを食べた猫がいました。
BACK INTO ENGLISH
There used to be a cat that ate mice.
INTO JAPANESE
昔はネズミを食べた猫がいました。
BACK INTO ENGLISH
There used to be a cat that ate mice.
That didn't even make that much sense in English.