YOU SAID:

Once I went to a park and there was a very old man and he was eating corn

INTO JAPANESE

私が公園に行ったとき、とても年上の男性がいて、彼はとうもろこしを食べていました

BACK INTO ENGLISH

When I went to the park, there was a very older man, and he was eating corn

INTO JAPANESE

私が公園に行った時、とても年上の男性がいました、そして彼はトウモロコシを食べていました

BACK INTO ENGLISH

When I went to the park, there was a very older man, and he was eating corn