

一晩で雪が町全体を覆ってしまいました。
恥ずかしくて、両手で顔を覆いました。
黒い雲が空を覆うと、急に寒くなった。
"おおう(覆う)" is in the lesson "Verbs 18" (Level 30), 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.