Conjugating -er and -ir verbs
After -ar verbs (lesson 7), the other two regular groups are -er and -ir. Their endings are almost identical — they only differ in the nós form (-emos vs -imos). Today: comer, beber, viver, escrever (-er); abrir, partir, dormir (-ir).
The -er group
Take comer (to eat). Stem: com-. Endings: eu como, tu comes, ele come / ela come / você come, nós comemos, eles comem / elas comem / vocês comem. The chant: -o, -es, -e, -emos, -em.
The -ir group
Take abrir (to open). Stem: abr-. Endings: eu abro, tu abres, ele abre / ela abre / você abre, nós abrimos, eles abrem / elas abrem / vocês abrem. The chant: -o, -es, -e, -imos, -em. Identical to -er except in the nós form.
Side by side: -ar vs -er vs -ir
eu: falo (-ar), como (-er), abro (-ir). tu: falas, comes, abres. ele: fala, come, abre. nós: falamos, comemos, abrimos — only place where -er and -ir part ways. eles: falam, comem, abrem. So the only forms you really need to keep separate across all three groups are the eu form (always -o) and the nós form.
More -er and -ir verbs
beber (to drink) → bebo, bebes, bebe, bebemos, bebem. viver (to live) → vivo, vives, vive, vivemos, vivem. escrever (to write) → escrevo, escreves, escreve, escrevemos, escrevem. partir (to leave / depart) → parto, partes, parte, partimos, partem. dormir (to sleep) is regular in most forms but the eu form drops a vowel: durmo, dormes, dorme, dormimos, dormem — a small wrinkle, common in -ir verbs.
viver vs morar
Both translate as 'to live', but they cover different turf. morar = to reside, to have your address somewhere. viver = to live (in the broader sense — to be alive, to lead a life). Moro em Lisboa = I live (am based) in Lisbon. Vivo bem = I'm living well / I have a good life. Vivo em Portugal also works for residency, especially in Brazilian Portuguese where viver is more common in this sense.
