National Geographic
@NatGeo
Step into wonder and find your inner explorer with National Geographic 🌎
参加 November 2008
179 フォロー中 28.1M ファン
@LuisvonAhn @duolingo When von Ahn heard that his language-learning app had become a vital teaching tool in refugee camps, his company waived the fees for over 135,000 displaced and low-income students for its English proficiency test.
もっと見る
