this/these= here, that/those= there
We use this and these for things that are here (near). This is singular and these is plural.
- This is my new watch.
- These are my sisters Anna and Jenny.
We use that and those for things that are there (not near). That is singular and those is plural.
- That man is very strange.
- I need those boxes over there.
With a noun or without a noun
We can use this, that, these, those with a noun (this box, that car, etc.) or without a noun.
- This watch is very expensive.
- I like that woman in the park.
- Who is that? (= that person)
- ‘What are those?’ ‘They are old pictures.’
This is John (introductions and on the phone)
We use this is when we introduce people and on the telephone.
- Hi, this is Tim. (Tim on the telephone)
- Laura: ‘Hi, Sara. This is my friend Paul.’ Sara: ‘Hi, Paul. Nice to meet you.’