The modal verbs

A modal verb never describes an action by itself; it tints another verb with ability, obligation or intention. können reports that something is possible for you, müssen that it is required of you, wollen that you intend it. Two habits have to grow at once. The first is that these verbs are irregular in the singular and carry no ending whatever in the ich and er/sie/es slots — ich kann, ich muss, ich will — so the bare stem that looks unfinished is precisely the right form. The second is the bracket the sentence forms around them: the modal is conjugated in second position while the main verb falls to the very end and remains an infinitive, as in Ich muss heute arbeiten. Everything else — the time, the place, the object — is packed between those two poles, and the practice below checks both ends of that bracket.