auxiliary verbs / helping verbs

The common auxiliaries are be, have, do, and the modals can, could, may, might, must, shall, should, will, would. Helping verb is the school name for the same words. After a modal or do, use the bare verb: can go, did go. After forms of have, and after forms of be in the passive, use the past participle: has gone, had gone, was seen. After forms of be in the progressive, use the present participle: is going. Do not add to after a modal: not can to go.