Note how, for each of the verb groups, the conjugations in the singular change but, in the plural, the endings are nearly always predictable ("-um", "-ið" and "-a", respectively). Most English present verbs are regular and have only one change in ending ("-s" for third person singular). In most cases in Icelandic, the conjugation patterns remain regular across most verbs. A verb's conjugation cannot be determined from its infinitive. Speakers must memorize which conjugation group a verb belongs to. Strong verbs fall into six groups augmented by reduplication verbs, each with exceptions (such as auxiliary verbs, the r-verbs, and the only verb in Icelandic that has been called 'totally irregular', "valda"). There is a classification system for all verbs, with the paradigms going into the dozens.