Check alternative answers?
Many times, when Duolingo asks me to translate a question, I am tempted to type an idiomatic answer, but instead I play it safe and type an answer that is clunky yet correct. After Duolingo tells me my clunky answer is correct, I want to be able to check alternate answers, just to see whether Duolingo would accept them. Can I do this in Duolingo? I hate the idea that I must stick with clunky unidiomatic answers.
The problem is that most sentences have a couple of hundred translations. So simply looking it up would not be possible. Usually if you chose a 'clunky' translation, duolingo shows you an alternative translation. Often this is a more idiomatic translation (but I agree, not always).
To add to what FrankySka said, sometimes if you check the sentence discussion people will post alternative sentences that Duolingo accepts. (If you ever find spam in that area, feel free to send me a link to it via my Activity stream and I'll come clean it up ^_^). You can also comment there, giving your idiomatic answer. Sometimes native speakers come in and answer questions like that.
You'll find the sentence discussion after you've already submitted an answer. It should be towards the bottom of the screen. It will look like this or similar to this (depending on which layout you have):