This was a real garden path for me! I kept wondering how 'you' made sense until I finally remembered 'bạn' also means friend. It seems to be an inherent problem of language learning material that we use 'tôi', 'bạn' and 'nó' so much in learning, but in everyday situations it would apparently be more common to use personal names or kinship terms. But this is not Duolingo's fault of course.
I don't think they wanna get people confused. Also unless you're Vietnamese, people don't expect you to use terms like chú, bác, thím, mợ etc.
What if you are talking to older people, say 20+ years older than you? It seems like 'bạn' might not be respectful enough.
I meant that you would still know some of the terms like ông, bà, cậu, cô, anh, chị, em... but not the more specific ones like thím (your younger brother's wife) or dượng (your mother's brother's wife/maternal uncle's wife).
Ah, I see. In fact I just read over the kinship term family tree in Thompson 1965 ('A Vietnamese Reference Grammar') yesterday. It is complicated, but not impossible. Luckily it seems like it's only really complicated if you have Vietnamese family or in-laws…if you don't, you can probably get away with only using a few kinship terms! (And if you do, the sheer force of repetition would bring it home soon enough, I'm sure.)
Why is "Make friend with me" a wrong translation? How can I know the number of people addressed by this sentence? Sometimes Duolingo uses its own rules quite inconsistently...
In English, you have to say 'Make friends with me'; 'make friend with me' is ungrammatical. The number of addressees cannot be explicit in the sentence, in this case. There are ways to make it explicit, of course: compare 'be my friend!' with 'be my friends!'
I think it should also accept the literal translation, which would be the 100X less awkward way of saying it: Make friends with me! NO ONE in the English-speaking world is ever going to say "Befriend me" in the command form. (It could be part of a larger sentence, as in "I was hoping he would befriend me." But it is simply not used in command form. Also, the word befriend is more generally used for an animal-human relationship. Not WRONG for human-human, but just a little stilted.