I just studied about relative clauses and I know that they should tell us which person or thing the speaker means. So when I'm in a conference and a woman is speaking can I ask my friend
"Do you know that woman who is speaking?"
or should I say "Do you know that woman speaking?"?
or when someone is talking to my friend Tom can I ask my friend
"Do you know the woman who is talking to Tom?"
or should I say "Do you know the woman talking to Tom?" ?
and why?? when should I use relative clause and when -ing and -ed phrases?