(My answer to this question at Quora.com)
- To a man or boy: Ha’im atah medaber ivrit?
- To a woman or girl: Ha’im at medaberet ivrit?
- To more than one person: Ha’im atem medabrim ivrit?
- Informally (which is usually the case), one drops the word Ha’im, which is the equivalent of the French Est-ce que.