<https://www.sunnysidejapanese.com/post/\u610F\u5730\u60AA\u30D9\u30F3\u30C1\u3010lower-intermediate\u3011>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.sunnysidejapanese.com/post/%E6%84%8F%E5%9C%B0%E6%82%AA%E3%83%99%E3%83%B3%E3%83%81%E3%80%90lower-intermediate%E3%80%91>