Ellipsis and Substitution

What are ellipsis and substitution?

Both help us avoid repeating words. In substitution, we replace words with a short word like one, do or so. In ellipsis, we simply leave words out because the listener already knows them.

"Do you need a bag?" — "No, I've got one." (substitution: one = a bag)

"Can you drive us?" — "Sorry, I can't." (ellipsis: I can't drive you)

Without these, English sounds slow and unnatural: "No, I've got a bag. Sorry, I can't drive you."

How to use substitution

One and ones (for nouns)

Use one for a singular countable noun and ones for plural. Use them with an adjective, with this/that/which, or with "the ... that".

Do not use one/ones for uncountable nouns (water, advice, information). Leave the noun out or repeat it.

Do, does and did (for verbs)

Use a form of do to replace a verb phrase in the present simple or past simple.

Do so (more formal)

Do so replaces a whole action. It is common in formal writing and instructions.

• If you wish to cancel, please do so before Friday. (do so = cancel)
• He promised to call, and he did so the next day.

So and not (for clauses)

After verbs like think, hope, expect, suppose, guess, believe and I'm afraid, use so for a positive answer and not (or a negative verb + so) for a negative answer.

Hope and I'm afraid only take not: "I hope not", not I don't hope so. With think, "I don't think so" is the everyday form; "I think not" is formal or old-fashioned.

How to use ellipsis

1. After auxiliaries and modals

Keep the auxiliary (be, have, do, will, can, should ...) and leave out the rest of the verb phrase.

• "Have you finished?" — "Not yet, but I will soon."
• I'd help you if I could.
• "Is it raining?" — "Yes, it is."
• She hasn't paid yet, but her husband has.

This is also how short answers and question tags work.

2. After "to"

Keep to and leave out the verb after it. This is common after want, would like, would love, try, need, have to, used to, going to.

• "Do you want to come?" — "I'd love to."
• You don't have to if you don't want to.
• I didn't call her, but I meant to.

3. In clauses joined by and, but, or

When two clauses share the same subject or verb, you can leave it out the second time.

• She opened the box and (she) took out the phone.
• I can't sing or (I can't) dance.
• Ana ordered the salmon, and Marco (ordered) the steak.

The last pattern (leaving out the verb in the middle) is more common in writing.

4. In short replies

In conversation we often answer with just the important words.

• "Where are you going?" — "To the bank."
• "When does it start?" — "At seven."
• "Who's driving?" — "Me."

5. In casual speech

In informal speech, people often drop the subject and the auxiliary at the start of a sentence. Do not do this in formal writing.

Substitution vs ellipsis

Sometimes you can choose: "She works harder than I do." (substitution) or "She works harder than me." (informal).

Common mistakes

1. Using one for uncountable nouns

• Wrong: I don't like cold coffee. I prefer hot one.
• Correct: I prefer hot coffee. / I prefer it hot.
• One and ones replace countable nouns only.

2. Using "a one" without an adjective

• Wrong: I don't have a pen. Can you lend me a one?
• Correct: Can you lend me one?
• Say "one" on its own, or "a + adjective + one" (a red one).

3. Using "I don't hope so"

• Wrong: "Will it rain tomorrow?" — "I don't hope so."
• Correct: "I hope not."
• With hope and I'm afraid, use "not".

4. Dropping "to" after want, like and love

• Wrong: "Would you like to join us?" — "Yes, I'd love."
• Correct: "Yes, I'd love to."
• Keep "to" when the verb after it is left out.

5. Leaving out a verb form that is different

• Wrong: I have never and will never agree to this.
• Correct: I have never agreed and will never agree to this.
• You can only leave out a word if the same form fits both places. "Have" needs "agreed", not "agree".

6. Using "I know so"

• Wrong: "Is the shop open on Sunday?" — "Yes, I know so."
• Correct: "Yes, I know." / "Yes, I think so."
• "Know" does not take "so" in replies.

Quick reference

Common questions

Is it "I hope not" or "I don't hope so"?

"I hope not" is correct. "I don't hope so" is not used. The same is true for "I'm afraid not".

Is "I think not" correct?

Yes, but it sounds formal, old-fashioned or a bit dramatic. In everyday English, say "I don't think so".

Can I say "So do I" and "Neither do I"?

Yes. "So + auxiliary + subject" agrees with a positive sentence, and "Neither + auxiliary + subject" agrees with a negative one: "I love snow." — "So do I." / "I can't ski." — "Neither can I."

Practise next

• Question Tags — the same auxiliary-only pattern at the end of a sentence
• Conjunctions — joining clauses with and, but and or
• Participle Clauses — another way to make sentences shorter
• Register: Formal and Informal Grammar — when casual ellipsis is fine
• Quiz: Ellipsis, Substitution and Participle Clauses — test yourself at C2 level