YOU SAID:
Haven't I taught you better?
INTO JAPANESE
私はあなたにもっと良く教えていませんか?
BACK INTO ENGLISH
Aren't I teaching you better?
INTO JAPANESE
私はあなたにもっとよく教えていませんか?
BACK INTO ENGLISH
Aren't I teaching you better?
That didn't even make that much sense in English.