What this is about
Three ways to say you must, need, or should do something — a scale from iron obligation to gentle advice: ter que → precisar → dever. Plus the profession rule (why it's "sou professor", not "sou um professor").
The obligation scale
| tenho que trabalhar | I HAVE TO — hard obligation, no choice |
| preciso trabalhar · preciso de café | I NEED to — necessity |
| você deve descansar | you SHOULD — advice, expectation |
In every tense you know
| Tive que sair cedo. | I had to leave early (perfeito) |
| Antigamente eu tinha que acordar às cinco. | I used to have to… (imperfeito) |
| Vou ter que trabalhar no sábado. | I'm going to have to… (future) |
Professions — delete the article
| Sou professor. · Ela é engenheira. | after ser: NO um/uma |
| but: Ela é UMA engenheira ótima! | the article returns when an adjective joins |
| Estou de férias! | estar de = temporary status (on vacation, off duty) |
Exceptions & details
1 · ter DE: you'll also see tenho de trabalhar — same meaning, slightly formal. Pick que and stay consistent.
2 · dever also means "to owe": Você me deve dez reais! Context separates advice from debt.
3 · deve ser = "it must be" (guessing): Ele deve estar cansado — obligation grammar doing probability work. B1 expands this.
4 · as férias is always plural: minhas férias começam em julho.
Practise this chapter
10 pool questions plus generated ones — 20 fresh practice questions, reshuffled every visit, inside the grammar library.
Practise Ter que, precisar & dever — 20 questions →This chapter is taught in Lição 16 of the course (level A2). Rumo is a complete Brazilian Portuguese course, A1 to B2; level A1 is free.