YOU SAID:
I washed my cat yesterday
INTO JAPANESE
私は昨日猫を洗った
BACK INTO ENGLISH
I washed the cat yesterday.
INTO JAPANESE
私は昨日猫を洗った。
BACK INTO ENGLISH
I washed the cats yesterday.
INTO JAPANESE
私は昨日猫を洗った。
BACK INTO ENGLISH
I washed the cats yesterday.
That didn't even make that much sense in English.