Inflexion During Conjugation
In addition to the verbal derivatives, the following changes may occur to the stem's suffix -a, during conjugation:
- The -a changes to -e to form the perfect subjunctive tense and certain tenses of the negative conjugation. This vowel always causes the syllable carrying it to assume a high tone.
- The -a changes to -e to form the present-future tense of the subjunctive mood.
- The -a becomes -ang to form the plural of the imperative and certain relative tenses.
- The -a becomes -ile to form the perfect stem. Various phonological situations may change this basic construct.
The general rules for the formation of the perfect are varied due to various mostly phonological interactions with the suffix:
- Generally, -ile is suffixed
- -reka buy ⇒ -rekile bought
- Verbs ending in -ya replace it with -ile
- -tsamaya go ⇒ -tsamaile went
- For monosyllabic stems, i-stems suffix -ile and e-stems suffix -ele
- -nwa drink ⇒ -nwele drank
- Disyllabic verbs ending in -ma change it to -mme
- -roma send ⇒ -romme sent
- Polysyllabic verbs ending in -sa, -tsa (most), -tswa, and -ntsha cause the -ile to alveolarise to -itse
- -hlatswa wash ⇒ -hlatswitse washed
- Verbs ending in -na of more than one syllable and disyllabic reciprocal verbs change the -na to -nne
- -bina sing ⇒ -binne sang
and so forth...
For all verbs, however, the past tense may also be indicated with the simple -ile (past subjunctive) multi-verbal conjugation, although its meaning does diverge somewhat from that of the perfect (especially with stative verbs)
- Ba ile ba bina They did sing
Read more about this topic: Sotho Verbs