"Alex is not a woman, but a man."
Translation:Alex ist keine Frau, sondern ein Mann.
Aber cannot be used for mutually exclusive alternatives and if there is no possibility to have none of the options:
- Ich habe kein Bier, aber (ich habe) Wein. (I could as well have no drinks at all, or both)
- Heute ist nicht Freitag, sondern Dienstag. (Today must be one of the days of the week, there is no none-day, and no two days at once)
'Sein' leaves things that the object 'is' as nominative. 'Einen' would be the accusative form.
I suppose formally in both the English and German sentences, an elipsis was used (the part in brakets can be omitted):
Alex ist keine Frau, sondern [er ist] ein Mann.
Are the elipsis rules the same for both English and German? Or is there an example where you can leave out part of a sentence in one language, but not the other?
Still a little confused on why it is not "sondern einen mann". Could someone explain more for me?