This / that / these / those

1. Demonstrative determiners

Demonstrative determiners are mostly used to specify or point to people, animals or things according to their proximity or distance, taking into account the position of the speaker:

2. How are demonstrative determiners used?

Demonstrative determiners are used according to location and number, taking into account the position of the speaker:

THIS 

It is used when we talk about a single item located at a short distance from the speaker.

This vase is very expensive.

THESE

It is used when we talk about more than one item located at a short distance from the speaker.

These shoes are old.

THAT

It is used when we talk about a single element that is at a certain distance from the speaker.

That boy is my cousin.

THOSE

It is used when we talk about more than one element located at a certain distance from the speaker.

Those toys are dirty.

We also use the demonstrative determiners when we introduce someone or ask for someone over the phone, using the constructions This is.../These are... and Is that...?, respectively:

Hi Mary. This is my boyfriend, Ron.

Hello Miss, these are my parents.

- Hello? Is that Sarah?

- No, it's her mother.

3. What is the function of the demonstrative determiners?

In order to know if the demonstrative acts as an adjective or a pronoun, it is important to consider the following aspects:

• When the demonstrative is accompanied by a noun, it is categorized as an adjective because it determines the element we are talking about.
  This apple is mine.

  I like that hat.
• If they don't accompany a noun it means that they are replacing a noun mentioned before or that can be deduced from the context, so in these cases we are dealing with a pronoun.
  These are original.

  That is not mine.

¡Remember!