Questions & Answers about O ilu książkach rozmawialiście?
Why do we use ilu instead of the standard ile (how many)?
The preposition o (when meaning 'about') requires the Locative case. In Polish, quantifiers like ile must decline to match the grammatical case. The Locative form of ile is ilu.
Is ilu only used for feminine nouns like książkach in this case?
No, the Locative form ilu is actually used for all genders! Whether you are talking about books (o ilu książkach), cars (o ilu samochodach), or men (o ilu mężczyznach), the word ile will always become ilu in the Locative case.
Why does the noun take the form książkach here?
Because it follows the preposition o, the noun must be in the Locative case. Since we are asking 'how many', it must be plural. The Locative plural ending for almost all Polish nouns, regardless of gender, is -ach.
What does the ending of rozmawialiście reveal about the people being asked?
The suffix -liście indicates the past tense for 'you' (plural) in the masculine personal form. This tells us that the group being addressed includes at least one male. If the speaker were talking exclusively to females, the verb would be rozmawiałyście.