sometimes 3 goes at testing out is not enough
I just got failed while trying to test out on prepositions, I challenged each of the four "wrong" answers as I felt I was correct in each case. I would like to suggest that when there are three challenges in a test that the student should get an extra "life" so that he can try a fourth time if necessary.
I am kind of torn on this. The point it to see whether or not you've "mastered" this stuff. I think three is plenty, even if it's annoying and inconvenient that you have to start over.
*But I see what you mean about the hassle of getting the answer wrong if it should have actually been a correct answer. The French section is still in beta so hopefully this will a short-term problem. (Oh, and by the way, what were the ones you got wrong that you say should have been accepted as correct answers?)
I don't remember what they all were now, usually a day or so after a challenge I get an email saying it has been acted on, so I can probably tell you then. One was the translation of Unwillingly, duolingo gave its answer as malgré que, I used sans vouloir, and got marked wrong; I challenged it as a valid alternative. What do you think? It was unusual to have that number of challenges in one section, I'm used to one or two but rarely four. Only one of the phrases had an actual mistake by duolingo: le instead of de - or the other way round, the others were valid alternative translations that it didn't recognise.