"Are there any countries you've become interested in since starting teaching on DMM?"
- "Are there any countries you've become interested in since starting teaching on DMM?"
"Are there any countries you've become interested in" 「興味を持った国はありますか」
"to be interested in ~" 「興味を持った〜」
"since starting teaching on DMM" 「DMMで教え始めてから」"since you started teaching on DMM" も使えます。
"since ~" 「〜から」
"starting teaching" 「教え始めて」
"on DMM" 「DMMで」
What countries other than Japan have you become interested in since you started teaching at DMM?
この場合、次のような言い方ができますよ。
ーWhat countries other than Japan have you become interested in since you started teaching at DMM?
「DMMで教え始めて、日本以外のどの国に興味を持つようになりましたか？」
countries other than Japan「日本以外の国」
to become interested in ... で「…に興味を持つようになる」
ご参考まで！
オーストラリア 
カナダ 
