This document discusses modals in English. It defines modals as auxiliary verbs that add meaning to sentences. There are modals like can, could, may, might, must, ought to, shall, should, will, and would. Modals show attitudes like necessity, advisability, or possibility. The rules for using modals are that the main verb is not conjugated and no "to" is used between the modal and main verb. Questions use the modal before the sentence. Negation uses "not" after the modal. Examples show modals for requests, requirements, prohibitions, suggestions, and the past form "should have."