"Carrie does not live in the mountains."
Translation:كَري لا تَسْكُن في ٱلْجَبَل.
actually your answer is correct. I would say report it but not sure if this would work.
On the other hand... the order of words or SVO can change in Arabic... it can be VSO and even VOS at times. Nonetheless, your sentence has the same meaning as their sentence and it should be correct.
I set my daily goal to 20 points. I do exercise daily on various languages so i don't get bored.
No language can be mastered in Duolingo. Specially Arabic.
I'm a native speaker of Arabic, rather a dialect, and still can't say I master it. I do learn new things (specially that I was not a good student in high school).
Arabic here on Duolingo is not the perfect choice but it will do to learn some words. The course here lacks a lot of grammatical stuff and made a mix of standard and various dialects; This is what I call (traveler's Arabic).
It is even better. The purest Arabic puts the verb before the subject, but this course is not pure Arabic, it mixes different dialects amongst classical Arabic. If you want to speak with poor and uneducated people, this will be of use, but if you wish to speak to university educated people, follow the news or write a letter, it does not show a high level of Arabic. For Moroccons this is not a very natural form of Arabic, though they will mostly understand you and be pleased that you try.