In the modern languages, the various classes have mostly been leveled into a single productive class. Icelandic, Norwegian and Frisian have retained two productive classes of weak verbs. (In Frisian, in addition to the class with -de, there is a class of je-verbs, where the dental suffix has dropped, i.e. -je < -iad.) Swiss German also has two types of weak verbs, descended from Class I and Classes II and III respectively of Old High German weak verbs and marked with -t and -et, respectively, in the past participle.