suggestion: edit/second chance
When we translate or type our answer, it would be nice if it gave us a second chance (or an option for a second chance). Maybe bold or highlight the words correct, and a second chance to fix our mistakes. I tend to not repeat them if I get a chance to catch them as oppose to someone saying "you're wrong".
Duolingo is running tests with lessons in which students are able to fix their mistakes. There is a version in which fixing a mistake gives half a heart in return. If this version proves to be successful it might become available to everyone.
I also had lessons in the past that didn't give me back half a heart for fixing mistakes. Instead I had multiple opportunities to fix something which I liked a lot because the half a heart option might make lessons too easy.
I'm in that test group as well. I first do a lesson on my iPad, where that option is not available. If I'm really struggling with a lesson and can't pass it on the iPad, I swith to the website where I can correct my mistakes to regain half a heart. This both allows me to finish the difficult lesson, while at the same time reinforcing the correct translation by having me type it out myself. It doesn't apply to all question types, but I really appreciate it for what it does apply to.
If you get into that test group, don't rely on it. I was in it and ended up with a false sense of security about how much I was learning. But, really I was being allowed to pass lessons with 7 errors per 20 questions.