I want to practice the hard questions
Is there a way to practice the harder sentences? When I try to go back and practice things I've done, I feel like well over half of the questions are "Sie spielt" or "Der Mann lernt", or other dead easy questions, which I think are starting to waste my time. It would be nice if I could somehow just practice the hard ones, or the ones I'm not yet comfortable with.
I think this is something to be expected in the near/far future. Duolingo is still in Beta. :) If you would let me guess a statistics software similar to Khan Academy will be implemented.
Right now though, The closest thing you can get to doing "hard" questions is to repeat individual lessons; click the skill you want to train on on your skill tree, then to the right of the page under "achievements" you can practice individual lessons.