

谷に向かって叫ぶと、きれいなエコーが返ってきます。
洞窟の中で話すと、エコーがすごく響くね。
山で「ヤッホー」と言ったのに、エコーが聞こえなかった。
"エコー" is in the lesson "Nature" (Level 38), 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.