YOU SAID:

I can't believe you have done this.

INTO JAPANESE

私はこれを行っているなんて信じられない。

BACK INTO ENGLISH

Can't believe I have done this.

INTO JAPANESE

これを行っているなんて信じられない。

BACK INTO ENGLISH

Can't believe you are doing this.

INTO JAPANESE

これをやっているなんて信じられない。

BACK INTO ENGLISH

Can't believe I'm doing this.

INTO JAPANESE

01317: これをやっているなんて信じられない.

BACK INTO ENGLISH

01317:Can't believe I'm doing this...

INTO JAPANESE

01317: これをやっているなんて信じられない.

BACK INTO ENGLISH

01317:Can't believe I'm doing this...