English grammar rule Did baseform
John did went to the theatre.
Do, does, or did can be used as helping verbs in some sentences. They’re also able to add emphasis to a main verb, ask a question, or form a negative (used with not). If the main verb is combined with do, does or did, they always use the base form.
Incorrect They do not makes enough products. Correct They do not make enough products. Incorrect Jim did not made the show. Correct Jim did not made the show.
Incorrect Does Jimmy enjoys dancing? Correct Does Jimmy enjoy dancing? Incorrect Did you turned out the lights? Correct Did you turn out the lights?
Incorrect I do thinks you are lying. Correct I do think you are lying. Incorrect The boy did ate my sandwich! Correct The boy did eat my sandwich!