I. Strong Verbs.
The strong verbs do not form the preterit with an additional suffix, but by change of the radical vowel or by reduplication. Thus, we hav two subdivisions:
1. Ablaut Verbs. The preterit of these verbs is formd without reduplication. It differs from the present only by a regular change of the radical vowel, the so-calld ablaut (cp. [§ 29]); e. g., binda, I bind, band, I bound.
2. Reduplicating Verbs. The prt. has reduplication, but no ablaut; e. g., halda, I hold, haíhald, I held.
3. Reduplicating Ablaut Verbs. A smaller number of verbs hav the prt. both with ablaut and reduplication; e. g., lêta, I let; laílôt, I let (prt.).
II. Weak Verbs.
The weak verbs form the preterit by the addition of a suffix beginning with a dental consonant; e. g., nasja, I save, nasida, I saved. This suffixal element, -da, was formerly regarded as a form of the verb 'do' (Germanic dôn), wherefore the weak prt. was also calld 'compound preterit'.
The weak verbs (except a few) ar derivativ verbs. According to their formativ suffixes, which ar best preservd in the preterit forms, they ar divided into four classes: (1) Suffix i (in the present j): nasja, nasi-da. (2) Suffix ô: salbô, salbô-da. (3) Suffix ai (in the present in part obscured): haba, habai-da. (4) Suffix nô (in the present n): fullna, fullnô-da.
Note. The small number of verbs which can not be referd to the two chief classes must, according to this classification, be considerd 'irregular'.