´we are three´ sounds very unnatural to me. Native speakers would normally say, ´there are three of us´- which is currently being marked are incorrect.
As above, 'we are three' in English sounds like a group of three year old children telling their age.
In Ireland, we wouldn't say "including mom", but "Mum included": "There are three of us, Mum included". Moreover, "We are three" doesn't mean : "Somos três", but "Temos três anos".
Allow me to strongly disagree: the Irish-English word is "mam". "Mum" is just another English word shipped over to Ireland through English TV...
Earlier in the lesson there was the same sentence but starting with Nos somos. Which one is correct?
Yeh, I've never heard a native English speaker say this. French speakers of English do, because they say it the same way in French. 'we are three' sounds like a group of small children announcing their age.
Maître d': "How many?" Customer: "We are three." ...or "There are three of us."
Either can be used, and maybe there is yet another way to say the same thing. It never occurred me that it could be referring to someone being age three.
Are you from the US? 'we are three' is not English as spoken in England. When AA Milne wrote 'Now we are six', he wasn't referring to a party of six people going to the Hundred Acre Wood.