@alex zorach maybe you missed the memo but this course is in beta ie a soft launch so they can get thousands of users and find/fix bugs. Pointing out additional translations is always appreciated but your tirade is not.
Not recommending you do it but if you're in China, you may often hear people skipping the verb itself and saying "你会英语歌吗？or 你会不会 英语歌? It's informal to be sure but seems to be used quite often. I'm not asking Duo to accept it but in case it confuses you.....
The above should be accepted, I think. I reported it. Let me know if I'm wrong, though. BTW, I think 你会不会唱英语歌？mean "Will you sing English songs?" and is distinct from my entry above. Is that correct?