YOU SAID:

I'm gonna eat some cookies

INTO JAPANESE

私はいくつかのクッキーを食べるつもりです

BACK INTO ENGLISH

I am going to eat a few cookies

INTO JAPANESE

私は、いくつかのクッキーを食べるつもり

BACK INTO ENGLISH

I was going to eat some cookies.

INTO JAPANESE

私はいくつかのクッキーを食べるつもりだった。

BACK INTO ENGLISH

I was going to eat some cookies.