YOU SAID:

Am I the only one who doesn't know the purpose for this

INTO JAPANESE

私はこの目的を知らないだけです

BACK INTO ENGLISH

I just do not know this purpose

INTO JAPANESE

私は、この目的を知りません

BACK INTO ENGLISH

I do not know this purpose

INTO JAPANESE

私は、この目的を知りません

BACK INTO ENGLISH

I do not know this purpose