❶be interested in ～ で～に興味を持っている, ～に関心を持っている; ～に参加する[～を買う]気にさせられている
He is (very) interested in Japanese history.
He is (very) interested in Japanese history.
彼は日本の歴史に（たいへん）興味がある.
Are you interested in the book?
Are you interested in the book?
君はその本がおもしろいですか.
I am interested in studying foreign languages.
I am interested in studying foreign languages.
私は外国語の勉強に興味がある[勉強をしたいと思っている].
⦣ 前置詞 in＋動名詞 studying （勉強すること）.
I'm more interested in literature than in mathematics.
I'm more interested in literature than in mathematics.
私は数学よりも文学に興味がある.
He became more and more interested in gardening.
He became more and more interested in gardening.
彼は園芸にだんだん興味を持つようになった.
I'm most interested in Japanese literature.
I'm most interested in Japanese literature.
私は日本文学に最も興味がある.
