YOU SAID:
The cat threw a party for all of its friends and they loved it.
INTO JAPANESE
猫は友達全員のためにパーティーを開き、彼らはそれを愛していました。
BACK INTO ENGLISH
The cat had a party for all his friends and they loved it.
INTO JAPANESE
猫は彼のすべての友人のためにパーティーを開き、彼らはそれを愛していました。
BACK INTO ENGLISH
The cat had a party for all his friends and they loved it.
That didn't even make that much sense in English.