"Last year was a good year."
もうしました。i'll presume that the reason this language course is so... unpolished, we'll say, is because of how odd japanese is in comparison to most other languages in duolingo's class set. what with the nondistinction between present and future, singular and plural, definite and indefinite, the frequent use of pro-dropping, and the whole topic-comment thing, i think the main problem duolingo is facing is that their own infrastructure wasn't prepared enough to deal with such a unique language. though that this course has already become the 7th most popular one on their entire site for English-speakers should show that there's a lot of demand for this one to improve.
ps what the actual ❤❤❤❤ are those score levels
It's not the course that's unreliable, but Japanese itself. Almost all kanji have at least a couple of readings, and two of the ones that Duolingo has taught us for this kanji happen to be ねん and とし. とし is the kunyomi reading, and ねん is the onyomi reading, and basically the kunyomi is used most on it's own, and the onyomi is used most when making other words. For example the official word for "year" is pronounced とし, but words like "last year", "next year", "the year after next", ”grade", etc., have the pronunciation ねん. It's possible to guess, but sometimes it can be unreliable and you just have to memorize the word.