Vaak kun je een zelfstandig naamwoord vervangen door one wanneer je het herhaalt of wanneer je antwoord geeft op een vraag:
Which skirt are you going to buy? The white one.
This new bag is black, my old one was green.
I like your bike, did you buy a new one?
Bij meervoud gebruik je ones:
I'm going to buy new trainers because my old ones have holes in them.
These brown belts are cheaper than the black ones over there.
There are lots of jeans to choose from. Which ones do you like best?