Modal Auxiliary Verbs
Modal auxiliary verbs work alongside main verbs to indicate the "mode" of action in a sentence. They add crucial information about permission, possibility, obligation, or future intent to your sentences. The English language has 13 modal auxiliaries: can, shall, must, could, should, ought to, dare, may, will, used to, might, would, and need.
Each modal has a specific job in sentences. Can and could express permission or possibility ("June can eat if she's hungry"), while shall and will show future actions or determination ("You shall attend the ceremony"). When you need to express strong obligation, use must ("We must tell the truth"), and for logical necessity, try should ("We should attend the interview if we want the job").
Some modals have specialized uses. Ought to expresses expectations ("Every student ought to study hard"), while dare typically appears in negative sentences ("You dare not touch that bag"). For possibility, use may or might ("It might rain this afternoon"), and for polite requests or conditional statements, would works well ("I would love to come with you"). Need shows necessity ("You need to leave now"), while used to describes past habits ("We used to fly kites when we were young").
Remember this! Modal verbs never change form regardless of the subject (I can, she can, they can) and are always followed by the base form of the main verb (without "to" except for "ought to").