YOU SAID:

This is that thing I was telling you about.

INTO JAPANESE

これは、私が話していたことです。

BACK INTO ENGLISH

This is what I was talking about.

INTO JAPANESE

これは、話していたものです。

BACK INTO ENGLISH

This is what were talking about.

INTO JAPANESE

これは何について話していたです。

BACK INTO ENGLISH

Talk about what it was.

INTO JAPANESE

それがだったものについて話してください。

BACK INTO ENGLISH

It was a talk about things.

INTO JAPANESE

物事についての話だった。

BACK INTO ENGLISH

It was a story about things.

INTO JAPANESE

ことにについての話だった。

BACK INTO ENGLISH

That to was talking about.

INTO JAPANESE

それについて話していたこと。

BACK INTO ENGLISH

You were talking about it.

INTO JAPANESE

あなたはそれについて話していた。

BACK INTO ENGLISH

You were talking about it.