- Translate: "You shouldn't eat so much sugar."
Answer: Você não deve comer tanto açúcar.
Dever expresses advice, so "não deve comer" means 'shouldn't eat'. "Não pode comer" is tempting, but it means 'can't' or 'aren't allowed to', which is a stronger prohibition than advice.
- Complete with "need to": "Nós ___ estudar para a prova amanhã."
Answer: precisamos
The subject nós (we) takes the -amos ending, so "precisamos" is correct. "Precisam" is also plural, but it goes with eles/elas/vocês, not nós.
- Which sentence is written correctly in Portuguese?
Answer: Ela precisa de um computador novo.
Before a noun, precisar needs "de": "precisa de um computador". "Ela tem estudar" is wrong because obligation with ter needs "que": "tem que estudar". Querer and dever take the infinitive with no preposition.
- You want to ask a classmate for permission to use their pen. Which word starts the question: "___ usar sua caneta?"
Answer: Posso
"Posso" (Can I / May I) from poder is used to ask permission. "Devo" means 'should I', which asks for advice about an obligation, not permission to borrow something.
- Complete with "can": "Eu ___ ir à festa no sábado."
Answer: posso
Poder is irregular in the eu form: "eu posso". "Podo" looks logical because regular -er verbs end in -o (como, bebo), but it is not a real form of poder.
