Can you help me? I want to talk about things, persons, ideas (about time, not location) that have already been talked about or are already known, and they are not here at this time, I don't know them is close to speaker or not close to speaker, so can I use the word "This, That, These, Those" as the follow conversations: 1. Am I correct if I can't see this pen at this time and can I use the word "that"? A: I have a nice pen. B: Is this pen a pencil? A: Yes, this pen is a pencil. 2. Am I correct and can I use the word "that"? A: I've just got a present. B: Is this present a pen? A: Yes, this present is a pen. 3. On the phone, am I correct and can I use the word "that"? A: I'm skating with some people. B: Are these people profesional skaters? A: Yes, these people are profesional skaters 4. Am I correct if this person is not here at this time and can I use the word "that"? A: I have a friend who can sing very well! B: Is this person a singer? A: Yes, this person is a singer. Thank you!