Germanic strong verbs form the tenses by using a vowel shift called 'ablaut' in the root of the verb.
Based on different vowel shifts, strong verbs were grouped in 6 categories.
Additional category is used for reduplicated verbs.
Thus, there are 6+1 groups.
Group I
| | Old English | Old Swedish | Modern Swedish |
|---|
| | ī - ā - i - ī | ī - ē - i - ī | i - e - e - i |
| Infinitive | bītan | bīta | bita |
| Past, Sg.3 | bāt | bēt | bet |
| Past, Pl.1 | biton | bitum | bet |
| Past participle | gebīten | bītin | bitit |
Group II
| | Old English | Old Swedish | Modern Swedish |
|---|
| | ēo - ēa - u - o | iū - ø - u - u | ju - jö - jö - ju |
| Infinitive | bēodan | biūþa | bjuda |
| Past, Sg.3 | bēad | bøþ | bjöd |
| Past, Pl.1 | budon | buþum | bjöd |
| Past participle | geboden | buþin | bjudit |