One

We commonly useoneand its pluralonesas a substitute for a countable noun:

A:

What about a cake?

B:

All right. Thank you. But I’m trying to slim, so I’ll just have a smallone.

A:

Can you fetch the DVDs from the shop?

B:

Whichones?

A:

Theoneswe ordered last week. The musicals.

We don’t useoneto refer back to uncountable nouns:

A:

Have you got any milk?

B:

Yes.

A:

Can I borrowsome?

Not:Can I borrow one?

As a noun substitute, we don’t useonesimmediately aftersome, any, bothand numbers, unless it is premodified:

A:

Are there any mangoes for dessert today?

B:

Yes, Nuala boughtsomeat the supermarket.

Not: …bought some ones at…

A:

How many pens did you buy?

B:

I boughtfour greenonesandsix redones.That should be OK, shouldn’t it?(The underlined words are premodifiers.)

In informal English,my, his, her, etc. (possessive determiners) can come beforeone. This makes the statement more emphatic:

A:

I couldn’t use my laptop today.

B:

Neither could I.My onegot stolen. (more emphatic thanMinegot stolen.)

Whenonerefers back to a previous noun and is premodified, a determiner (a/an,the, this, your) must be used:

The hotel that we had booked turned out to bea luxuryone.

Not:The hotel that we had booked turned out to be luxury one.

I liked all your songs, but Yesterday wasyour bestone.