

鍵を電車に忘れるなんて、私は本当に馬鹿です。
誰も君のことを馬鹿だなんて思ってないよ。
人の失敗を見て馬鹿にするのはやめてください。
"ばか(馬鹿)" is in the lesson "Emotions" (Level 42), along with 11 other useful words. LinDuo has 180 topic lessons like this one, 2,379 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.