Studying German, learners come across modal verbs expressing desire, ability, obligations or probability. In German, we conjugate the modal verb, which retains the second position in the main clause. The main verb is added in its infinitive form to the end of the sentence.
For example: Ich darf meine Hausaufgaben nicht vergessen.
What is the English speaker’s main challenge when using these verbs in German? English speakers use ‘must’ plus a negator to express something that is not permitted. Indeed, you’ve heard your German tutor say: You must not forget your homework. The clanger many English speakers fall for in German is to translate this verbatim by using ‘müssen’ with a negator plus the main verb. However, in German, ‘nicht müssen’ leaves another option and translates as ‘doesn’t have to’. To express something that is forbidden (verboten), German uses the modal verb ‘dürfen’ plus a negator: nicht dürfen = verboten. Remember, you must not forget your homework.
Sie dürfen Ihre Hausaufgaben nicht vergessen.