YOU SAID:

I ate some potatoes yesterday

INTO JAPANESE

昨日はポテトを食べました

BACK INTO ENGLISH

I had potato yesterday.

INTO JAPANESE

私は昨日じゃがいもを食べました。

BACK INTO ENGLISH

I ate the potatoes yesterday.

INTO JAPANESE

私は昨日じゃがいもを食べた。

BACK INTO ENGLISH

I ate the potatoes yesterday.