Your (and my) primary problem here is confusing Spanish/Portuguese "comer" with Italian "mangiare". But if you translate correctly the first word, you will catch the mistake in the second. Especially when the subject phrase and/or verb usually come first (after any interrogative/adverb/interjection).
- Sei come tua mamma = You are
eats(???) your mom
Regarding the issues with the use of definite articles and family members, I found these links which are very helpful. I have been living in Italy with my fiancee for several months, and I can confirm that this is most often the case (except in very archaic books or dialect, of course) http://italian.about.com/library/fare/blfare124a.htm http://blogs.transparent.com/italian/mamma-mia/
Now, if only Duolingo could be a bit more consistent where it pertains to these rules!
In this context, 'be like your mom' would be like a command, and would therefore require the imperative mood. I believe the second person singular of 'essere' in the imperative is 'sii', so it would be 'Sii come tua mamma'. I think :) Similarly, expressions like 'be a man' would be rendered as 'sii uomo'.
Interesting...I'd been thinking of "proprio" as only meaning "(one's) own," but do you mean that in this context, it can mean "exactly" and modify "come" instead of modifying "sei"? If that's not how the meaning comes about, how does it work? When I see "Sei proprio come tua madre!", it seems to me to literally mean "You-yourself (only (just) you?) are like your mother," but I don't think that's what "x is just like y" means in English.
It's not that the space is limited.. it's the amount of manual effort required to add each additional term. It's not a matter of just adding the word; you have to add every permutation of the new word and possible answers. That's just crazy. Just stick with the most common terms. This is not a website for one to get creative with their translation. It's a place to help one understand what one is learning.
DL needs to get its act together on English. Mom is never used in Britain, we use mam in north east England and Scotland, mum in the south (although it sounds wrong to me), and mam or mammy in Ireland I think. Also, in the north and in Ireland, we say Ma - all of these are standard English and the equivalent of mom.
I simply do. I have no problems with other Americanisms. It is a statement of fact for me so I am sure you can't possibly be offended? You do seem a bit cross. US usage would accept mother or mum. I am not sure about most people being Americans on here. That's a bit of a conclusion.
I didn't say that most people on here are Americans. Please reread my post. I just can't imagine you advocating that the word used by most Americans not be accepted here. Mum sounds super funny to me but I would never think to suggest that it not be accepted. Tolerance, my friend, tolerance.