関連ワード:  how long does it take to learn a second language    how long does it take to learn a new language    how long does it take to learn a new language on duolingo    how long does it take to learn a foreign language    how long does it take to learn a new language fluently    how long does it take to learn a new language as an adult    how long does it take to learn a new language on average    how many hours does it take to learn a new language    how long can it take to learn a new language    how many years does it take to learn a new language  
結果 : how long does it take to learn a second language