YOU SAID:
renefren my knee hurts gaah
INTO JAPANESE
私の膝はガアーが痛い
BACK INTO ENGLISH
Gaa hurts on my knee
INTO JAPANESE
Gaaは私の膝が痛い
BACK INTO ENGLISH
Gaa hurts my knees
INTO JAPANESE
Gaaは私の膝を痛めます
BACK INTO ENGLISH
Gaa hurt my knee
INTO JAPANESE
Gaaは私の膝を痛めた
BACK INTO ENGLISH
Gaa hurt my knee
That didn't even make that much sense in English.