Verb "sein" (być)

Learners forget that być requires instrumental case with nouns (jestem studentem, not *jestem student). The 3rd plural są looks nothing like the rest of the paradigm. English speakers: Use nominative after być (*jestem student) instead of instrumental (jestem studentem). Omit być entirely when not needed. Russian speakers: Russian drops быть in present tense — must remember to include jestem/jest. Instrumental after быть is familiar (я студентом → jestem studentem). Czech speakers: Czech jsem/jsi/je maps directly. But Czech uses nominative after být (jsem student) — Polish requires instrumental (jestem studentem).