"Do you like playing the guitar?"
Translation:Gitar çalmayı seviyor musun?
I just looked it up in my 2011 Grammar book "Turkish: An Essential Grammar" by Göksel and Kerslake. P. 254 ff. deals with it well. But it is much too complicated to deal with here. Best perhaps to model usage on examples given in Duolingo....who is doing his owlish best, but can really only give us the broad outlines:) I agree, this particular point is frustrating.