"The weather is cold."
I received this sentence in my practice and I can never remember which lesson exactly the sentence is from. I think there needs to be an indication for politeness & formality.
Yes, this is a huge problem with the Korean Duolingo, when you just use the "Strengthen" buttons it gives you random things from all sorts of lessons and you have no way of knowing which conjunction they want. The worst part is that the conjunction they DO want often isn't listed as a dictionary hint when you hover over words.
SAME!!!! I always put 는 or 가 after the topic/subject and I always get it wrong because the answer is the other thing and I don't know why it's wrong!!!