Another category of verbs is “mixed” or weak irregular verbs. As the name suggests, these verbs have features of both regular and irregular verbs. With the exception of “wissen,” all mixed verbs look regular in the present tense: they have no stem vowel changes (e.g. schlafen, essen, geben) and no spelling irregularities (like the verb “haben”).
The mixed verbs include: wissen, brennen, kennen, nennen, rennen, denken, and bringen. The past tense forms of these verbs is where we see the irregular elements:
bringen → brachte
denken → dachte
kennen → kannte
Clearly, there are stem vowel changes (unlike regular verbs), so these verbs are mix of weak (i.e. regular) and strong (i.e. irregular) verbs. Here are the present tense conjugations of these verbs:
As mentioned above, the verb “wissen” is exceptional, in that it contains a stem vowel change AND it has the same conjugation for the “ich” and “er/sie/es” forms.