YOU SAID:

I don't know who did it, but somebody farted.

INTO JAPANESE

誰がそれをしたのかわかりませんが、誰かがおならしました。

BACK INTO ENGLISH

I don't know who did it, but someone fart.

INTO JAPANESE

誰がそれをしたのかわかりませんが、誰かおならです。

BACK INTO ENGLISH

I don't know who did it, but someone is farting.

INTO JAPANESE

誰がそれをしたのかわかりませんが、誰かがおならをしています。

BACK INTO ENGLISH

I don't know who did it, but someone is farting.