When I say "I talk to you" in English it's non-optional to have a temporal tense (the above is in the present) but optional to have a spatial tense (you don't know where it is happening).

In lojban you can say "mi do tavla" (or "mi tavla do") and that doesn't specifically give the temporal or spatial tenses. But you can add both to any degree.

So "mi pu tavla do" means I spoke to you in the past, "mi puzu tavla" means it was a long way in the past, and so on.

More details: https://lojban.github.io/cll/10/1/