"Aren't you sitting?"
Translation:¿Tú no te sientas?
How do you know that it's not common? My Colombian husband told me the "-ndo" form is used almost as often as we use "-ing" in English, only limited to whenever someone is in the process of doing something, as you say, which is still very common. He disagrees with Duolingo's insistence on encouraging translations of English "-ing" words into simple Spanish present tense instead of "-ndo" words.
I would understand why Duolingo marked me wrong for inputting "No estás sentandote?" if they had used "Do you sit down?" or "Are you seated?," but they didn't.
I responded with "No estás sentando", and was told it was a typo, and it was corrected to "No estás sentado". Does anyone know why the "n" is dropped here? Is it just a random irregularity or is there some rule I'm missing? Also does this mean the reflexive "te" isn't necessary in this tense? I forgot about it until I looked at the discussion board.
I'm not certain it's a rule-- but Spanish does NOT use the Gerundio (a verb in its -ando or -iendo/the equivalent of the English Present Participle -ing word) as a noun or an adjective!
In English a Present Participle can function as a noun (an English gerund) or an adjective or an adverb!
The Spanish Present Participle (un gerundio) can only be used to make one of the Progressive Tenses or to act as an adverb modifying certain verbs like seguir and several others!
In Spanish--when one wants to use a verb to function as an adjective--one must use the past participle!
Duo's sentence is not a very clear example of this difference between English and Spanish because either way means essentially the same thing!
It could be, depending on the context; but that would be pushing things.
Where I could see using it in the present progressive is if someone was sitting and said "I wish i has time to sit for just five minutes". Then a present progressive response could be "aren't you sitting?"
I think what Duo is looking for is more the meaning "aren't you sitting today?" or "aren't you going to sit?"
I would tend to use the "aren't you..." when someone is not doing what everyone else is and you want to start a conversation about it or invite them to. When everyone is getting ready to eat except one person: "Aren't you eating?" with a possible response about dieting or plans to eat elsewhere. At a dance hall: "Aren't you dancing?" with possible responses of no one to dance with, or injury or lack of knowledge.
"Aren't you sitting" isn't really something I can see in American English. But British English would be part of "aren't you sitting for this test." (American English would be taking the test.)