The verb to undo · Conjugation
Past Continuous of undo
The answer: was / were undoing
B1
An action in progress in the past, often interrupted.
Quick answer
The Past Continuous of the verb to undo is was / were undoing.
Example: I was undoing the knot when the phone rang.
Full conjugation in the Past Continuous
| Pronoun | Form |
|---|---|
| I | was undoing |
| You | were undoing |
| He / She / It | was undoing |
| We | were undoing |
| You (pl.) | were undoing |
| They | were undoing |
Common mistakes to avoid
1. You was / They was ❌
Use was only with I, he, she and it. Use were with you, we, they and plural nouns: you were undoing, my friends were undoing. You always takes were, even when you talk to one person.
2. They were undo ❌
The Past Continuous needs both parts: was or were + the -ing form. They were undo forgets the -ing. They undoing forgets were. The correct form is they were undoing.
3. I was knowing ❌
State verbs (know, understand, want, need, like) are not normally used in the continuous. In the past, use the Past Simple: I knew the answer, not I was knowing the answer.
Practice quiz
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Frequently asked questions
How do you conjugate undo in the Past Continuous?+
Use was or were (the past of be) + the -ing form undoing. Use was with I, he, she and it. Use were with you, we and they: I was undoing, they were undoing.
When do you use the Past Continuous of undo?+
Use it for an action in progress at a moment in the past: At 8 o'clock, I was doing my homework. It often describes a long action, and a short action interrupts it: I was having a shower when the phone rang. The short action is in the Past Simple.
What is the difference between I undid and I was undoing?+
I undid (Past Simple) is a finished action, seen as one complete event. I was undoing (Past Continuous) is the same action in progress, like the background of a story. Compare: I did my homework and I was doing my homework when you called.
Is it when or while with the Past Continuous?+
Both are possible, but they usually go with different actions. While goes with the long action, in the Past Continuous: While I was walking home, it started to rain. When usually goes with the short action, in the Past Simple: I was walking home when it started to rain.
How do you make the negative and the question of undo in the Past Continuous?+
Negative: add not after was or were: I wasn't undoing, they weren't undoing. Question: put was or were before the subject: Were you undoing…?, Was she undoing…? Do not add did: Did you were undoing? is wrong.
Related pages: undo Past Continuous
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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-continuous
© 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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