We don't capitalize pronouns in this course, because the sentences are totally out of context.
But it is a very good practice to capitalize all versions of singular "you" (some people do that also with plural "you", but to me it somehow looks strange), when you are addressing someone directly. So in letters, e-mails, text messages, facebook messages, comments on Duolingo etc. - yes, it is good to capitalize them. But not when you are for example writing dialogues in a book, or telling a story via fb messenger and noting that someone said something with the word "you".
No, that's not possible.
For 2nd person singular in Genitive (and in Accusative as well), there are two options: neutral 'cię' and emphatic 'ciebie'. At the beginning of the sentence, only the emphatic form could be used.
But that's very rare anyway, it does not feel natural. "Ciebie nie znamy" would be like "Him - we know, Her - we know, You - we do not know..."
Can you give a couple of examples where ciebie woyld be used instead of cie?
And then also a couple where it would be used at th beginning and with the reason why.
Also, like cie has ciebie, do the others (first person singular, third person plural, etc etc - all 6) do they have a -bie form or equivalent too?
Sorry thats a few questions in one comment
Please help me to understand something. There is a sentence in this lesson, "She does not see you," that is translated as „Ona ciebie nie widzi." This sentence is, "we do not know you," which is translated „Nie znamy cię". For the former example, „Ona nie widzi cię" is not accepted. What is the difference between these sentences wherefore the latter can end in cię („Nie znamy cię") but the former cannot?