Questions & Answers about Kupiliśmy chleb, masło oraz ser.
Why does the verb kupiliśmy end in -śmy instead of -łyśmy?
Kupiliśmy is the masculine personal form (used when the "we" includes at least one man). If the group saying "we bought" consisted entirely of women, they would use the non-masculine personal form kupiłyśmy.
Why use the perfective verb kupiliśmy here instead of kupowaliśmy?
Kupiliśmy shows that the action was completed as a single, finished event: you bought the groceries and the task is done. Kupowaliśmy (imperfective) would mean "we were buying" (focusing on the background process) or "we used to buy" (a repeated habit).
These nouns are direct objects. Why haven't chleb, masło, and ser changed their dictionary endings?
They are in the accusative case (the direct object form), but their accusative forms happen to look exactly identical to their dictionary forms (nominative). Chleb and ser are inanimate masculine nouns, and masło is neuter. For these specific noun types in the singular, the ending doesn't change.
What is the difference between using oraz and i for "and"?