There are no definitive rules for how the past tense stem of a verb stem is formed, but there are common patterns. The following table lists the most common past tense stems based on how the verb stem ends. The example verbs are given without the infinitive prefix.
| Stem ending (present) | Stem ending (past) | Examples |
|---|---|---|
| -ba | -bye | saba → -bye, hamba → -hambye |
| -da | -ze | kunda → -kunze, doda → -doze |
| -ga | -ze | haga → -haze, funga → -funze |
| -ha | -shye | boha → -boshye, taha → -tashye |
| -ka | -tse | shaka → -shatse, cika → -citse |
| -ma | -mye | soma → -somye, rema → -remye |
| -na | -nye | korana → -koranye, fana → -fanye |
| -nnye | kina → -kinnye | |
| -nya | -nyije | koranya → -koranyije, fatanya → -fatanyije |
| -nye | tinya → -tinye | |
| -nywa | -nyijwe | teganywa → -teganyijwe, menywa → -menyijwe |
| -ra | -ye | sura → -suye, tera → -teye |
| -ze | kora → -koze, gura → -guze | |
| -reye, -riye | hera → -hereye, sinzira → -sinziriye | |
| -rwa | -we | terwa → -tewe, girwa → -giwe |
| -zwe | gurwa → -guzwe, korwa → -kozwe | |
| -rewe, -riwe | kererwa → -kererewe, hirwa → -hiriwe | |
| -sa | -she | mesa → -meshe, rasa → -rashe |
| -sheje, -shije | kerensa → -kerensheje, cugusa → -cugushije | |
| -sha | -sheje, -shije | reshya → -reheje, tashya → -tahije |
| -shwa | -shejwe, -shijwe | koreshwa → -koreshejwe, igishwa → -igishijwe |
| -shya | -heje, -hije | hosha → -hosheje, fasha → -fashije |
| -shye | beshya → -beshye | |
| -ta | -se | hita → -hise, rata → -rase |
| -she | fata → -fashe | |
| -tsa | -keje, -kije | otsa → -okeje, atsa → -akije |
| -za | -je | za → -je, sokoza → -sokoje |
| -jeje, -jije | koza → -kojeje, kiza → -kijije | |
| -zwa | -jwe | za → -je, sokoza → -sokoje |
| -jejwe, -jijwe | kizwa → -kijijwe |
Notice that when the past tense stem ending contains two vowels, the first vowel is subject to the A-I-U rule. For example -sha can become -heje or -hije depending on the preceding vowel:
Irregular verbs
Most single syllable verb stems are irregular, e.g.
Other stem changes
Sometimes more than just the ending of the verb stem changes, e.g.
