A.     Used as adjectives, they agree with their nouns in number. They are the only adjectives to do this.

This beach was quite empty last year

This exhibition will be open until the end of May.

These people come from that hotel over there

What does that notice say”’

That exhibition closed a month ago

He was dismissed on the 13th. That night the factory went on fire

Do you see those birds at the top of the tree”’

this/these/that/those + noun + of + yours/hers etc. or Ann’s etc. is sometimes, for emphasis, used instead of your/her etc. + noun:

This diet of mine/My diet isn’t having much effect.

That car of Ann’s/Ann’s car is always breaking down. Remarks made with these phrases are usually, though not necessarily always, unfavourable

B.     this/these, that/those used as pronouns:

This is my umbrella. That’s yours

These are the old classrooms  Those are the new ones.

Who’s that (man over there)”¹ ~ That’s Tom Jones. After a radio programme:

That was the concerto in C minor by Vivaldi. this is is possible m introductions:

ANN (to TOM): This is my brother Hugh.

ANN (to HUGH): Hugh, this is Tom Jones

TELEPHONE CALLER: Good morning. This is/I am Tom Jones . . . I am is slightly more formal than This is and is more likely to be used when the caller is a stranger to the other person. The caller’s name + here (Tom here) is more informal than This is. those can be followed by a defining relative clause:

Those who couldn ‘t walk were carried on stretchers this/that can represent a previously mentioned noun, phrase or clause:

They’re digging up my road They do this every summer

He said I wasn ‘t a good wife  Wasn ‘t that a horrible thing to say ^?

C     this/these, that/those used with one/ones

When there is some idea of comparison or selection, the pronoun one/ones is often placed after these demonstratives, but it is not essential except when this etc is followed by an adjective:

This chair is too low. I’ll sit in that (one).

I like this (one) best

I like this blue one/these blue ones.