Irregular
verbs are eccentrics. They change their vowel but normally not in a
manner we can identify as a pattern. In simple past, there are groups
of verbs with the same main vowel.
logen,
boten, hoben
The
vowel must be stressed.
They
look (and sound) as if they are from the same family, but in present
tense they have nothing to do with each other.
lügen
(to lie), bieten (to offer), heben (to lift)
Verbs
in simple past with a stressed a: kamen, baten, stahlen
Present
tense: kommen, bitten, stehlen.
But
there is some pattern:
Verbs
in simple past with a stressed u: trugen, fuhren, einluden.
Present
tense: tragen, fahren, einladen.
Some
simple past verbs with the stress upon ie stem from present
tense verbs with ei as the main vowel.
schrieben,
stiegen, blieben
Present
tense: schreiben, steigen, bleiben
So,
to get to the past, we just need to interchange the letters.
However,
other simple past verbs with ie stem from present tense verbs
with different vowels.
schliefen,
anriefen, hießen
Present
tense: schlafen, anrufen (to call on the phone), heißen
When
conjugated, they also differ from the verb-ending pattern as we know
it. They create their own pattern. Here are two examples (bieten and
bleiben).
ich bot blieb
du botest bliebst
er, sie, es bot blieb
ihr botet bliebt
wir, Sie, sie boten blieben
du botest bliebst
er, sie, es bot blieb
ihr botet bliebt
wir, Sie, sie boten blieben
Be
aware that this form of the past tense is often used in written
language. In spoken language we create the past with the perfect
tense combining haben or sein with the participle (gesungen, gegangen
etc.)