Savoir can mean to know something or to know how to do something. In this case a good translation would be "He knows how to be bad". If Duo accepts "He knows to be bad", that's a mistake.
I asked, "Can he do what is needed?". She responded, "He knows how to be bad."
if the right english translation is 'he knows how to be bad', then shouldn't the french equivalent be ' il sait comment etre mechant/mauvais' ?
The only hint for "etre mauvais" is "failed", although there are other hints for "mauvais". This makes me believed that the lesson would be to teach a special usage of "etre mauvais". Therefore, I made my input with "he knows that he is ailed". As all users who have practiced this exercise can expect, I was rejected.
If there were no hints at all, I would have understood the sentence as " he knows how to be bad" --which is the same as the answer by the system. Since the hint suggests something else, I thought I was wrong and choosed hinted answer.
I am writing here to complain the hints like this one. These hints do nothing to help the users but only mislead.
.. or maybe: he knows being bad -> he knows that he has been bad? advice please!
Can anyone provide a more working translation, more for my own piece of mind?
Action movies, mostly. Although it could come in handy if you get in with the "wrong crowd" in Paris.