

O colchão do hotel é muito duro.
Este queijo é duro ou mole?
O pão de ontem ficou duro.
"duro" is in the lesson "Properties" (Level 26), along with 9 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.