C. Demonstrative Pronoun: can use ‘this’ (singular) and ‘these’ (plural) as pronouns:
a. also use this, these, that and those with nouns to show proximity. We can us ‘this’ to talk about people or things near us (e.g. This is a nice cup of tea.) and to introduce people (e.g. This is Ann. These are my friends, John and Mike. (But, We don’t say. These are John and Mike.) We say. This is John and this is Mike.)
b. can use ‘this’ to introduce ourselves to begin a conversation on the phone. (e.g. Hello, this is Peter, Can I speak to Mary?)
C1. use ‘that‘ (singular) and ‘those’ (plural): We say ‘that‘ to talk about things that are not near us. (e.g. What’s that? This is our house, and that’s Bob’s house over there. Who are those people?)
a. also use ‘that’ to refer back to something someone said or did. (e.g. Shall we go to the cinema? Yes, that’s a good idea.)