1.The division of weak verbs into classes was based on the original stem-building suffix of a verb that was already hard to distinguish even in OE:
Class 1 | Infinitive | Past | Participle 2 | Basis for Subdivision |
OE | styrian | styrede | stured | stem-suffix -j most verbs – with front root-vowel derived from nouns, adjectives |
ME | stiren | stirede | stired | |
NE | stir | stirred | stirred |
Class 2 | Infinitive | Past | Participle 2 | Basis for Subdivision |
OE | lōcian | lōcode | lōcod | stem-suffix –oja most numerous class most verbs – with back root-vowel |
ME | looken | lookede | looked | |
NE | look | looked | looked |
Class 3 | Infinitive | Past | Participle 2 | Basis for Subdivision |
OE | libban | lifde | lifd | 3 verbsonly: habban (to have), libban (to live), secζan (to say) |
ME | livien | livde | lived | |
NE | This class merged with class 1 in ME |
2.Weak verbs were not as complex as strong ones and had a greater regularity and simplicity. That’s why they were productive, i.e. all borrowed verbs used weak model of form-building (suffix -t/-d) (e.g. Scand. to skate, Fr. to charm, Lat. to decorate, etc.) and, as it has already been mentioned above, many originally strong verbs turned into weak (e.g. to bake, to laugh, to help, to lie, etc.). The opposite process of turning of weak verbs into strong was very rare and was mainly based on phonetic similarity between some strong and weak verbs, i.e. was a result of mere confusion that later was accepted as a norm due to its persistent and regular character (e.g. to wear was originally weak and became strong because of the mistaken analogy with to swear, to ring (mistaken analogy with to sing), to hide (mistaken analogy with to ride)).