More variety please!
In the portuguese section, it gets quite annoying when you get the same question asked 3 times in different modes for a same lesson. I find myself learning the specific answers rather than the grammar.
Also there are some slang terms, "e daí" for example that are impossible to know for a non native speaker. Some sort of vocabulary for those would be awesome.
The reason duolingo asks a question multiple times is simply because they best way to learn is by repetition. Instead of just doing the same thing every time, they switch up the way they ask for the answer.