The verb to undo · Conjugation
Present Perfect of undo
The answer: have / has undone
B1
A past action with a link to the present.
Quick answer
The Present Perfect of the verb to undo is have / has undone.
Example: I have already undone the knot.
Full conjugation in the Present Perfect
| Pronoun | Form | Contraction |
|---|---|---|
| I | have undone | I've undone |
| You | have undone | You've undone |
| He / She / It | has undone | He's / She's / It's undone |
| We | have undone | We've undone |
| You (pl.) | have undone | You've undone |
| They | have undone | They've undone |
Common mistakes to avoid
1. I have seen him yesterday ❌
Do not use the Present Perfect with a finished time (yesterday, last week, in 2020, two days ago). Use the Past Simple: I saw him yesterday. With undo, use undid with a finished time and have undone without one.
2. I live here since 2020 ❌
Some situations started in the past and are still true now. For them, use the Present Perfect: I have lived here since 2020, I have known her for three years. Use since + a starting point (since Monday, since 2020). Use for + a length of time (for two weeks, for a long time).
3. I have undid ❌
After have or has, use the past participle, not the Past Simple: I have undone. The Past Simple of undo is undid, and the past participle is undone. Learn the three forms together: undo, undid, undone.
Practice quiz
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Frequently asked questions
How do you conjugate undo in the Present Perfect?+
Use have or has + the past participle undone. Use has with he, she and it. Use have with I, you, we and they: I have undone, she has undone. Short forms: I've undone, she's undone.
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.
When do you use the Present Perfect of undo?+
Use it for a past action that is connected to now, with no exact time. Use it for experiences in your life: Have you ever undone…? Use it for a recent action with a result now, often with just: I have just undone… Use it also for a situation that started in the past and continues: I have lived here since 2020.
What is the difference between I undid and I have undone?+
I undid (Past Simple) goes with a finished time: yesterday, last week, in 2020, two days ago. I have undone (Present Perfect) has no finished time, and the result is important now. Signal words: ever, never, already, just, yet.
How do you make the negative and the question of undo in the Present Perfect?+
Negative: I haven't undone, she hasn't undone. Question: put have or has before the subject: Have you undone…?, Has she undone…? The word yet often goes at the end of a negative or a question: Have you finished yet?
Related pages: undo Present 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/present-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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