This is a cruel sentence to have on audio. I know this duolingo language is all but abandoned at this point, but this is quite difficult for a beginner to understand. Shorter audio clips, PLEASE!
IMO the length is fine. Though a turtle option would be handy for those of us who struggle to distinguish the "d", "r", and "gi" of the North.
Space it out. "Những giáo sư" + "đang có một bài giảng dài" + "về động vật."
I was surprised but i've managed to hear it and i answered correctly with the first try (though i had to listen to it several times before answering), while usually i have problems with audio-tasks. So i guess the audio here is just ok!
bai giang dai means great lecture in my translator,is this right or not