

食べ物をかむ時は、口を閉じるのがマナーです。
歯医者さんに「はい、口を閉じてください」と言われました。
彼は何も言わずに口を閉じた。
"くちをとじる(口を閉じる)" is in the lesson "Head" (Level 44), 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.