YOU SAID:
Why can't this work for once!
INTO JAPANESE
なぜこれが一度だけ動作することはできません!
BACK INTO ENGLISH
Why can't this work just once!
INTO JAPANESE
なぜ一度だけこの仕事ができないのですか?
BACK INTO ENGLISH
Why can't I do this job only once?
INTO JAPANESE
なぜ私は一度だけこの仕事をできないのですか?
BACK INTO ENGLISH
Why can't I do this job only once?
You've done this before, haven't you.