"Do I put ice in their glasses?"
The Italian should read "Metto ghiaccio nei loro bicchieri?"
The given sentence "Metto ghiaccio nei bicchieri di loro?" is pretty unnatural.
Grazie! IT sounded unnatural to me even though I'm jjust learning! The ENGLISH is bad, too. We would say either "Should I put" or (more formal) "Shall I put"- never "do I put", unless it's an habitual act. Bad sentence. I reported it.
I would disagree, actually. If someone is preparing for a party, he might ask someone else, "Hey, do I put ice in the glasses?". Of course, what he means by that is "Should I put ice in the glasses?" but it wouldn't be unnatural for him to say it that way.