are you using …?
初期設定のまま使ってるの？
Are you using it with the default settings?
どのテキスト使ってるの？
What textbook are you using?
どの教科書を使ってるの？
Which textbook are you using?
それ使ってるの？
Are you using that?
その携帯いつから使ってるの？
How long have you had that phone?
この歯ブラシ、いつから使ってるの？
How long have you been using this toothbrush?