Grammar Rules and Exercises: How to Use “A”, “An”, “One”, and “Ones” Correctly
Grammar Exercise: “A” / “An” or “One” / “Ones”?
Understanding the difference between the articles A and An and the number word One can sometimes be tricky, especially for English learners. In this article, we’ll take a deep dive into the grammar rules behind A, An, One, and Ones. We’ll also provide practical exercises to help reinforce these concepts.
Rules for Using “A” and “An”
The articles A and An are used with singular nouns to indicate any general, non-specific object or entity. The choice between A and An depends on the sound that follows them:
A is used before words starting with a consonant sound.
- a dog
- a university (pronounced with a consonant sound /juː/)
An is used before words starting with a vowel sound.
- an apple
- an hour (even though the word starts with an “h,” it is silent, so the word starts with a vowel sound)
Important note: The decision between A and An depends on the pronunciation, not the spelling of the word. For example, the word “hour” starts with a silent “h,” so we say an hour.
Rules for Using “One”
One refers to a specific quantity, meaning “one” of something. It is used when we want to emphasize that we mean exactly one, rather than just any single item.
- One indicates a precise quantity:
- I have one brother.
- She bought one book.
The Difference Between “A” / “An” and “One”
A and An refer to any single, non-specific item.
- I need a pencil — any pencil, not a particular one.
One emphasizes that there is a specific number, exactly one.
- I need one pencil — I need exactly one, not more.
Rules for “One” and “Ones”
In addition to the number One, we also use One and Ones as pronouns to avoid repeating nouns. This helps make sentences more fluid and natural.
“One” as a Pronoun
One replaces a singular noun when we are referring to one specific item.
- This cake looks delicious. Can I have one?
- Do you have a pen? I need one.
“Ones” as a Pronoun
Ones replaces plural nouns when referring to multiple items.
- These shoes are nice. I like the red ones.
- I lost my keys, but I found the old ones.
Practice: “A” / “An” or “One” / “Ones”?
