Why do we use THIS and THESE?

We use this (singular) and these (plural) as pronouns:

• – to talk about people or things near us:

This is a nice cup of tea.
Whose shoes are these?

• – to introduce people:

This is Janet.
These are my friends, John and Michael.

WARNING:
We don’t say These are John and Michael.
We say This is John and this is Michael.

• – to introduce ourselves to begin a conversation on the phone:

Hello, this is David, Can I speak to Sally?

Why do we use THAT and THOSE?

We use that (singular) and those (plural):

• – to talk about things that are not near us:

What’s that?
This is our house, and that’s Rebecca’s house over there.
Those are very expensive shoes.

• – we also use that to refer back to something someone said or did:

– Shall we go to the cinema?
– Yes, that’s a good idea.

– I’ve got a new job.
– That’s great.

– I’m very tired.
– Why is that?

THIS, THESE, THAT, THOSE with nouns

We also use this, these, that and those with nouns to show proximity

… we use this and these for people or things near us:

We have lived in this house for twenty years.
Have you read all of these books?

… and that and those for people or things that are not near us:

Who lives in that house?
Who are those people?