YOU SAID:

Never have i ever killed two birds with one stone.

INTO JAPANESE

私は今までに一石二鳥の鳥を殺したことがない。

BACK INTO ENGLISH

I have never killed one stone and two birds.

INTO JAPANESE

私は一石と二羽の鳥を殺したことがない。

BACK INTO ENGLISH

I have never killed one stone and two birds.