YOU SAID:
There is a goat at this party!
INTO JAPANESE
このパーティーでヤギがある!
BACK INTO ENGLISH
This party is a goat!
INTO JAPANESE
このパーティーは、ヤギは!
BACK INTO ENGLISH
This party was the goat!
INTO JAPANESE
このパーティーは、ヤギだった!
BACK INTO ENGLISH
This party was a goat!
INTO JAPANESE
このパーティーはやぎでした!
BACK INTO ENGLISH
This party was a goat!
That didn't even make that much sense in English.