the strong verb system ceased to be productive: no new strong verbs developed. Practically all new verbs were weak, and few new strong verbs were created. Over time, strong verbs tended to become weak in some languages, so that the total number of strong verbs in the languages was constantly decreasing. The coherence of the strong verb system is still present in modern German, Dutch, Icelandic and Faroese. For example, in German and Dutch, strong verbs are consistently marked with a past participle in -en, while weak verbs have a past participle in -t in German and -t or -d in Dutch. In English, however, the original regular strong conjugations have largely disintegrated, with the result that in modern English grammar, a distinction between strong and weak verbs is less useful than a distinction between "regular" and "irregular" verbs. Thus, the verb to help, which used to be conjugated help-holp-holpen, is now help-helped-helped. The reverse phenomenon, whereby a weak verb becomes strong by analogy, is rare (one example in American English, considered informal by some authorities, is sneak, snuck, snuck. Another is the humorous past tense of "sneeze" which is "snoze"). Some verbs, which might be termed "semi-strong", have formed a weak preterite but retained the strong participle, or rarely vice versa. This type of verb is most common in Dutch: lachen lachte (formerly loech) gelachen ("to laugh") vragen vroeg (formerly vraagde) gevraagd ("to ask") An instance of this phenomenon in English is swell, swelled, swollen (though swelled is also found for the past participle, and the older strong form swole persists in some dialects as the preterite and past participle and has found new use in recent years. ). Conjugation As an example of the conjugation of a strong verb, we may take the Old English class 2 verb , "to offer" (cf. English "bid"). This has the following forms: While the inflections are more or less regular, the vowel changes in the stem are not predictable without an understanding of the Indo-European ablaut system, and students have to learn five "principal parts" by heart. For this verb they are . These are: The infinitive: . The same vowel is used through most of the present tense. In most verbs (other than classes 6 and 7), this represents the original ablaut e-grade. The present tense 3rd singular: . The same vowel is used in the 2nd singular. In many