

Sim, quero um café, obrigado.
Disseste sim ao convite do Rui?
Acho que sim, mas não tenho a certeza.
"sim" is in the lesson "Conversation" (Level 36), along with 15 other useful words. LinDuo has 180 topic lessons like this one, 2,380 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.