There are Four Principle parts that need to be memorized for most German Verbs:
- The Infinitive (present active) helfen
The 3 sg (present active) hilft
The preterit (simple past tense, literary past) half
The past participle (passive) geholfen
The infinitive form provides the present stem. Just remove the -en infinitive ending and add the person endings to form the present tense. However, many verbs also change the vowel for the 2 sg (familiar) and 3 sg forms; as with helfen above. Since the 3 sg also indicates the vowel change for the 2 sg; it is the second principle part. In verbs with no present tense vowel change the second principle part may be omitted. The last two principle parts should be learned with each new verb.
For a reading knowledge one can often recognize these forms or see patterns and make an educated guess without having memorized them. To compose or speak, however, one must know the proper forms.
Strong and Weak
Weak verbs in German have nothing to do with weak verbs in Hebrew and Semitic languages. In fact, German “weak” verbs seem more like “regular” verbs to English speakers.
Strong verbs, also called “N-verbs” are strong because they retain the old Germanic pattern of indicating the past tense by a vowel change (as English sing/sang/sung; run/ran). Another explanation for the designation “strong” is that the verb does the work of indicating tense internally by a vowel change, rather than taking the lazy way of simply adding -t to form the past tense. Strong, N-verbs form the preterit (simple past) by means of a vowel change; the participle ends in -en.
Weak verbs (“T-Verbs“) take the lazy way: They add -t to the preterit and to the past participle passive. Compare the Following:
- T-verbs (weak verbs) lernen lernte gelernt (inf, pret, ppc)
N-verbs (strong verbs) singen sang gesungen (inf, pret, ppc)
Some strong verbs also have a vowel change in the 2nd and 3rd sg forms. In these verbs the 3 sg form is inserted as the second principle part. Note the following example (principle parts in bold):
- brechen: ich breche, er bricht, ich brach, ich habe gebrochen
There are also a few mixed verbs that are both weak and irregular. They may include both the -t and a vowel change in the past tense: bringen, brachte, gebracht
Further, there are a few verbs that are just plain irregular.