Irregular VerbsPast tense of “undo”: undid, undone
The verb “undo” is irregular: its past simple is “undid” and its past participle is “undone”.
Base form (V1)
undo
/ʌˈnduː/
Past simple (V2)
undid
/ʌˈndɪd/
Past participle (V3)
undone
/ʌˈndʌn/
Meaning
to make something go back to how it was
Example
He undid the knot with his teeth.
Pattern
ABC — all three forms are different
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