"A década termina hoje" AGAIN
Does the phrase "A década termina hoje" really need to appear 4-5 times in every lesson?
check your vocab and see the last times that "década", "termina" and "hoje" were last seen. If it is something unexpected then maybe there is a bug in Duolingo.
I'll leave it to the folks in the engine room to figure out whether it is a bug, a design flaw, or a "feature," but I too see the same phrases come around again and again and again even though I figured them out correctly the first time they came up. This is not really a good way for us to be spending our time