YOU SAID:
eating ketchup isn't good for the teeth
INTO JAPANESE
ケチャップを食べるのは歯に良くない
BACK INTO ENGLISH
Eating ketchup is bad for your teeth
INTO JAPANESE
ケチャップを食べるのは歯に悪い
BACK INTO ENGLISH
Eating ketchup is bad for your teeth
That didn't even make that much sense in English.