Ab wann darf man wählen? Present and past modal verbs

Modal verbs express necessity or possibility. Use them with a 2nd verb in the infinitive at the end of the sentence. 'Dürfen' refers to permission required from another person. 'Können' refers to the ability to do something. The stems of modal verbs are irregular, with vowel changes in most singular forms. 'Sollen' is the exception. Modal verbs are mostly used in the imperfect tense when they describe past events. Remove any umlauts in the imperfect. [w] sounds like 'Welt', [qu] is pronounced the same as [kw] and sounds like 'bequem', and [zw] sounds like 'zwanzig'.