Note 1 — Chapter XIX · Strong Verbs: Classes II and III.
Reading edition
A few verbs of Class II have ū instead of ēo in the infinitive:
brūcan, brēac, brucon, gebrocen, to enjoy [brook].
būgan, bēag, bugon, gebogen, to bend, bow.
2. By a law known as Grammatical Change, final ð, s, and h of strong verbs generally become d, r, and g, respectively, in the preterit plural and past participle.
3. Cf. the Scotch “to dree one’s weird” = to endure one’s fate.