"wer bist du" and "wer sind sie"
So I don't understand when do I have to use "wer bist du" or "wer sind sie" can anyone please explain this to me ? Thanks in advance ;)
Sie can also be 3 person plural (they) or she. but if it is you (sing. formal) the s of Sie is always capitalized. even in the middle of the sentence. if it is in the beginning of the sentence you have to look at the verb form and the context to know what it is. (2. person sing. formal and 3. plural are using the same verb form thats why i say you have to look ate the context as well.) but du is always informal and Sie (with capitalized S) is usually formal. (if it is not in the biginning of the sentence. since the beginning of a sentence is always capitalized.)
so to be accurate your 2. sentence would usually be seen as who are they because the s was not capitalized.