That is a problem. I like using the app on my phone, because it is nicely designed for it (easier for my old eyes to read, among other things). When I start a new lesson, though, I open Duolingo in a browser window (I have an Android phone, so a Chrome window). The Tips & Notes show up there as a little light bulb icon now. Once I read the Tips & Notes, I then just go back to the app. Give it a try.
Good point-- I guess I just thought that in translation they might accept the fairly common spoken English question form which is "Don't you....?" This would seem to work with the way Vietnamese form their questions and could be an alternate choice (it might help people remember how không functions as well).
In the mind of the speaker it is a positive question, so it is translated as "do you".
They also have negative questions have the same subtle difference than in English (or Spanish). But they respond with the opposite answer we would expect (at least in Spanish). For example:
Don't you go to swim? Yes (means: yes, I don't go to swim).
The listening is too quick for me. I am not still good recognizing the tones, and even some sounds.
I am still at the point where I need to hear every word and translate in my mind, and with these audios I cannot differentiate one word from the following.
Do you feel that the speech is too quick for the level of this lesson?