When using the modal verbs in German language in combination with other verbs, we usually use
Their infinitive as a past participle.
So they always come after the infinitive verbs that depends on a finite verbs.
Look at this German example sentence:
Er hat es nicht machen dürfen
He wasn’t allowed to do it
Compare the above sentence with the following one with does not have any German modal verb:
er hat es nicht gemacht
he hasn’t done it
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