It's common to hear people use हो with आप while speaking, however it is not grammatically correct, but it's acceptable in some regions and perhaps is used more than [आप - हैं]. Peace.
aap~ho is used when talking to some elderly/senior with high familiarity or closeness or frankness... aap hai is used here to indicate general conversation between any two people with little familiarity and seniority gap is still maintained
I'm sure that for many other native speakers it's the other way round ;). I doubt if the आप-हो is an acceptable construction in Standard Hindi. It's certainly used in colloquial speech, although the usage varies from place to place. In my family, for instance, using हो (instead of हैं) with आप will be considered outright rude.
At my home we use, आप-हो always For example, आप क्या कर रहे हो ? आप क्यों रो रहे हो ? तुम कहाँ जा रहे हो ? & Thousands of examples like this. Not everyone uses आप while talking to Children & siblings, we can use तुम-हो combination then
That's correct, I acknowledged that आप-हो is used in colloquial speech and that its usage shows regional variation. Also, I wasn't trying to say that आप is used in all situations; my point was that I am more familiar with using हैं with आप (as opposed to हो with आप), not that हो isn't used at all.
Duolingo teaches the proper grammar of a language, not colloquialisms. In keeping with that trend, I think it's fair that your suggested sentence is not accepted.
My explanation to support my answer :
Just because a sentence is not in formal textbook language doesn't mean that it shouldn't be accepted. I personally think that The main aim why this course was kept in Beta by contributors in order to enable constructive arguments, improve the course & add as many solutions as possible. I always think that the language trend always depends on how people speak nowadays than the formal textbook language which you see nowhere in actual use. आप बहुत रोते हो । आप बहुत रोते है । तुम बहुत रोते हो । All of these are having perfect grammar structure & should be accepted because people use both तुम & आप