Command form: in the “du” form, the verb has the same root as the present tense, but does not include the -st ending or umlauts. The “ihr” form is the same as the present tense “ihr” form, but the word “ihr” is absent from the sentence (same as the “du” form). The verbs in the “wir” and “Sie” forms stay the same, but the “wir” or “Sie” goes after the verb.
The irregular and mixed verbs are strong verbs that do not follow the same pattern as the weak verbs and which also do not fit into the normal verb classes. Since they do not follow the pattern, they must simply be memorized.
Here is a list of irregular German verbs – first in present tense, then in the imperfect past tense, and last in the perfect past tense: gehen ging gegangen, kommen kam gekommen, sein war gewesen, stehen stand gestanden, tun tat getan, werden wurde geworden.
Here is a list of mixed German verbs following the same order as the first list: bringen brachte gebracht, denken dachte gedacht, haben hatte gehabt, kennen kannte gekannt, nennen nannte genannt, rennen rannte gerannt, wissen wusste gewusst.
The modal verbs and different verb classes will be posted at a later date (probably not all at once).