One and Ones — Substitution Pronouns

Practice using 'one' to replace a singular noun and 'ones' to replace a plural noun. Fill-blank, multiple-choice, error-correction and transformation exercises at difficulty 1–2.

One and Ones: Replacing Nouns to Avoid Repetition

English uses one (singular) and ones (plural) as substitution pronouns to avoid repeating a countable noun. This system is learnt at A2 but continues to produce errors at B1–B2, particularly with plural forms and in contexts where the pronoun must follow a determiner. Analysis of intermediate learner corpora shows that the single most frequent error is using 'one' where 'ones' is required — typically when the antecedent noun is plural but the learner treats the entire noun phrase as a single unit: 'Do you have cheaper one?' instead of 'cheaper ones'.

When to Use 'One'

Use one to replace a singular countable noun. It typically follows a determiner (the, this, that, a) or an adjective.

I don't like this shirt. Can I try the blue one? (one = shirt)
This chair is broken. Let's use the one by the window. (one = chair)
I need a pen. Have you got one? (one = a pen, indefinite)

When to Use 'Ones'

Use ones to replace a plural countable noun. It most commonly follows an adjective or a determiner such as 'which', 'these', 'those'.

I don't like these shoes. I prefer the ones in the shop window. (ones = shoes)
This hotel is expensive. Are there any cheaper ones? (ones = hotels)
Which cookies would you like? The chocolate ones, please.

What 'One/Ones' Cannot Replace

Neither 'one' nor 'ones' can replace uncountable nouns (water, information, luggage) or proper nouns. In those cases, repeat the noun or use a pronoun such as 'it' or 'some'.

Common Mistakes

✗ These shoes are expensive. Do you have cheaper one? → ✓ cheaper ones. (shoes is plural)
✗ Which jacket do you want? I'll take the black ones. → ✓ the black one. (jacket is singular)