YOU SAID:
don't you know i'm no good for you
INTO JAPANESE
私はあなたのために良いとは知らないのですか
BACK INTO ENGLISH
Do not you know I am good for you
INTO JAPANESE
私はあなたのために良いことを知っていませんか?
BACK INTO ENGLISH
I do not know good for you?
INTO JAPANESE
あなたには分かりません。
BACK INTO ENGLISH
You do not understand.
INTO JAPANESE
分かりません
BACK INTO ENGLISH
I don't know
INTO JAPANESE
わからない
BACK INTO ENGLISH
I don't know
That didn't even make that much sense in English.