"We have drunk water"
No, with the short verbs whose stems are only one syllable ...
- -la = to eat
- -nywa = to drink [Yes, this is one syllable!]
- -fa = to die
- -wa = to be
... the -ku- is kept in various situations. This includes with the positive markers for the present, past, perfect and future tenses.
kunywa = we drink
vs. hatunywi = we don't drink
kunywa = we drank
vs. hatukunywa = we didn't drink [the "ku" here is the negative past tense marker]
kunywa = we have drunk
ku)nywa = we have not drunk [the
ku is optional but fairly uncommon]
kunywa = we will drink
kunywa = we will not drink
Here are a bunch of other verbforms.
tukinywa = if we drink / (with us) drinking
tukanywa = and then we drank
tunywe = we should drink / let's drink
tusinywe = we shouldn't drink / let's not drink
kunywa = if we drank / we would drink
kunywa = if we had drunk / we would have drunk
kunywa = when we drank
kunywa = when we drink [present, habitually]
kunywa = when we drink [future]
As you can see, this
ku appears in some forms and not others. It's just a little quirk of Swahili grammar, but compared to, say, memorising lists of irregular verbs like "see, saw, seen; write, wrote, written; sing, sang, sung; sting, stung, stung; hang, hung, hung; bring, brought, brought", we're getting off pretty lightly.
I was (of course :) aware of the rules for one syllable stems (-la, -fa, etc), but not that -nywa should be treated as such.
So, I googled for the pronunciation of kunywa and found this other thread on Duolingo. Good to know!