Translation:Kilogram, gram, and milligram are units of weight.
Kilograms, grams, and milligrams are units of weight. <-- this is incorrect?
Since this is to learn Bahasa Indonesia (not English), does it really matter the accuracy of articles, plurals form etc? Let's the user focus on learning Indonesian, not English. Spanish lessons of duolingo could be a good reference for this.
PS: I am a native Indonesian, have IELTS band 8. Somehow, I am doing a lot better in Spanish and Catalan lessons than Indonesian. I can't even pass beyond mid-checkpoint because the answers are so rigid, especially in minor English grammatical problems.
I am not native Indonesian and not native English speaker either, so by doing this Indonesian course, I am learning correct English too. That being said, I perfectly agree with SisiFloren. It is the right thing to tell the administrator that the English translation is grammatically wrong, but I want them not to make the correct answers too rigid.