[Maxful]

Thanks for the help, masaegu.

Anyway, regarding ""かぎはあるの？", what I meant was, for example, Ralph is going to his grandmother's house with his brother Roy, but grandmother isn't going to be at home, so Roy asks if Ralph has the key to the house with him. So what should Roy say in this situation?

As for "持っています(か)", what is it use for? I assume it is only for things? Like for example:

自転車を持っています。

チョコレートのパンを持っているのです。

But I can't say

妹をもっています。

Correct?