English grammar rule Did past

Do, does, or did can sometimes be used as helping verbs. Sometimes, they add emphasis, form a question, or combine with not to express a negative. In these situations, use the root form of the main verb.

Examples of 'Did past' rule

Expressing negatives:

Incorrect	Polly do not keeps her receipts
Correct	Polly does not keep her receipts.
Incorrect	Tim did not attended the show.
Correct	Tim did not attend the show.

Asking questions:

Incorrect	Does Dorothy enjoys ice cream?
Correct	Does Dorothy enjoy ice cream?
Incorrect	Did you pushed the cart?
Correct	Did you push the cart?

Emphatic do:

Incorrect	I do thinks you are avoiding me.
Correct	I do think you are avoiding me.
Incorrect	The snake did coiled around the mouse!
Correct	The snake did coil around the mouse!