24.    Adjectives + one/ones and adjectives used as pronouns

A.     Most adjectives can be used with the pronouns one/ones, when one/ones represents a previously mentioned noun:

Don't buy the expensive apples; get the cheaper ones.

Hard beds are healthier than soft ones.

I lost my old camera; this is a new one.

Similarly with a number + adjective:

If you haven't got a big plate, two small ones will do.

B .    Adjectives used as pronouns

first/second etc. can be used with or without one/ones; i.e. they can be used as adjectives or pronouns:

Which train did you catch? ~ I caught the first (one).

the + superlative can be used similarly:

Tom is the best (runner).       The eldest was only ten. and sometimes the + comparative:

Which (of these two) is the stronger?

But this use of the comparative is considered rather literary, and in informal English a superlative is often used here instead:

Which (of these two) is the strongest?

Adjectives of colour can sometimes be used as pronouns:

I like the blue (one) best.

Colours of horses, especially bay, chestnut, grey are often used as pronouns and take s in the plural:

Everyone expected the chestnut to win.

The coach was drawn by four greys.