The verb to undo · Conjugation
Past Perfect of undo
The answer: had undone
B2
A past action that happened before another past action.
Quick answer
The Past Perfect of the verb to undo is had undone.
Example: She had already undone the knot when I arrived.
Full conjugation in the Past Perfect
| Pronoun | Form | Contraction |
|---|---|---|
| I | had undone | I'd undone |
| You | had undone | You'd undone |
| He / She / It | had undone | He'd / She'd / It'd undone |
| We | had undone | We'd undone |
| You (pl.) | had undone | You'd undone |
| They | had undone | They'd undone |
Common mistakes to avoid
1. I had undid ❌
After had, use the past participle, not the Past Simple: I had undone. The Past Simple of undo is undid, and the past participle is undone.
2. Yesterday I had gone to the cinema ❌
Use the Past Perfect only for the earlier of two past actions. For one past action, the Past Simple is enough: Yesterday I went to the cinema. With undo: undid for one action, had undone for the action that came first.
3. 'd + past participle = had
'd can mean had or would. Look at the next word. 'd + past participle = had: I'd undone = I had undone. 'd + base form = would: I'd undo = I would undo.
Practice quiz
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Frequently asked questions
How do you conjugate undo in the Past Perfect?+
Use had + the past participle undone. The form is the same for every person: I had undone, she had undone, they had undone. The short form is 'd: I'd undone.
When do you use the Past Perfect of undo?+
Use it for an action that happened before another action in the past. It shows which action came first: When we arrived, the film had already started. The film started first, and then we arrived. Signal words: before, after, already, by the time.
What is the past participle of undo?+
The past participle of undo is undone. You use it after have, has and had. It is different from the Past Simple. Learn the three forms together: undo, undid, undone.
What is the difference between had undone and have undone?+
Have undone (Present Perfect) connects the past to now. Had undone (Past Perfect) connects an earlier past to a later past. Compare: I have finished my homework (so I can play now) and I had finished my homework before dinner.
How do you make the negative and the question of undo in the Past Perfect?+
Negative: I hadn't undone (had not). Question: put had before the subject: Had you undone…? The past participle does not change.
Related pages: undo Past Perfect
Pages on a similar topic or with a similar use, so you can keep exploring.
Updated on 12 November 2026 by the Big Challenge teaching team. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999. Our teaching approach →
The Big Challenge · Updated on 12 November 2026 · Source: www.thebigchallenge.com/bl/academy/learn-english/verbs/undo/past-perfect
© The Big Challenge. Copying allowed for classroom use. Every year, more than 500,000 students across Europe take part in our English contest, created in 1999.
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More forms of the verb to undo are coming soon.