He is fluent in English and yet he is still a high school student.
こんにちは!
ご質問ありがとうございます。
『高校生なのに英語がうまい』は、
He is fluent in English and yet he is still a high school student.
と言えます。
『高校生で英語がペラペラの人がいました。』は、
There was a high school student who was fluent in English.
と表現できますね!
メモ
fluent in ~を流ちょうに操る、~に堪能である、~に精通する
and yet それなのに、それにもかかわらず、なおかつ
役立ちそうなフレーズ
English proficiency 英語力
speak fluently in English 流ちょうに英語で話す
参考になれば幸いです。
He's still just a high school student, but his English is really good.
He hasn't even finished high school, but his English is fantastic.
この場合、次のような言い方ができますよ。
ーHe's still just a high school student, but his English is really good.
「彼はまだ高校生なのに、英語がすごく上手だ」
ーHe hasn't even finished high school, but his English is fantastic.
「彼はまだ高校生なのに、彼の英語は素晴らしい」
ご参考まで!