Aaargh. That's British English. In the States we say "learned".
"You learnt their songs." Why is it not accepted?
Probably just because they haven't added it ... or they're unaware that "learnt" is also correct.
How is it indicates that it's songs plural?
By zao. Nyimbo is in class 10, which takes the z- concord and "their" is -ao.
I thought it was the z- but ive also seen other words where it's not z-, its y-. How do we choose which prefix to use? (In general, too, for words not obviously of a particular consonant class)