ONE and ONES

Question 1

We can use ONE (singular) and ONES (plural) instead of repeating the noun.

Don’t use ONE/ONES before uncountable nouns. We use SOME in this case.

We use SOME if the noun is unspecific.

Answer 1

Can I get you a drink? It’s okay, I have already got one.
I think his best poems are his early ones.

If you need more paper, I’ll bring you some.

We need new curtains. Let’s buy green ones this time.
We need new curtains. Let’s buy some.

Question 2

We can leave ONE/ONES out:
After WHICH.
After superlatives.
After this, that, these or those.
After either, neither, another, each, the first/second/last.

Question 3

We don’t leave out ONE/ONES:
After THE, THE ONLY, The main, every.
After adjectives.