The Lojban tense system interacts with the Lojban logical connective system. That system is a separate topic, explained in Chapter 14 and touched on only in summary here. By the rules of the logical connective system, Example 17.1 through 17.3 are equivalent in meaning:
17.1) la teris. satre le mlatu .ije la teris. satre le ractu
Terry strokes the cat. And Terry strokes the rabbit.
17.2) la teris. satre le mlatu gi'e satre le ractu
Terry strokes the cat and strokes the rabbit.
17.3) la teris. satre le mlatu .e le ractu
Terry strokes the cat and the rabbit.
Suppose we wish to add a tense relationship to the logical connective “and”? To say that Terry strokes the cat and later strokes the rabbit, we can combine a logical connective with a tense connective by placing the logical connective first, then the tense, and then the cmavo “bo”, thus:
17.4) la teris. satre le mlatu .ijebabo la teris. satre le ractu
Terry strokes the cat. And then Terry strokes the rabbit.
17.5) la teris. satre le mlatu gi'ebabo satre le ractu
Terry strokes the cat, and then strokes the rabbit.
17.6) la teris. satre le mlatu .ebabo le ractu
Terry strokes the cat and then the rabbit.
Example 17.4 through 17.6 are equivalent in meaning. They are also analogous to Examples 17.1 through 17.3 respectively. The “bo” is required for the same reason as in Example 16.2: to prevent the “ba” from functioning as a sumti tcita for the following sumti (or, in Example 17.5, from being attached to the following selbri).
In addition to the “bo” construction of Examples 17.4 through 17.6, there is also a form of tensed logical connective with “ke ... ke'e” (“tu'e ... tu'u” for sentences). The logical connective system makes Examples 17.7 through 17.9 equivalent in meaning:
17.7) mi bevri le dakli .ije tu'e mi bevri le gerku .ija mi bevri le mlatu tu'u
I carry the sack. And (I carry the dog. And/or I carry the cat).
I carry the sack. And I carry the dog, or I carry the cat, or I carry both.
17.8) mi bevri le dakli gi'eke bevri le gerku gi'a bevri le mlatu
I carry the sack and (carry the dog and/or carry the cat).
I carry the sack, and also carry the dog or carry the cat or carry both.
17.9) mi bevri le dakli .eke le gerku .a le mlatu
I carry the sack and (the dog or the cat).
I carry the sack and also the dog or the cat or both.
Note the uniformity of the Lojban, as contrasted with the variety of ways in which the English provides for the correct grouping. In all cases, the meaning is that I carry the sack in any case, and either the cat or the dog or both.
To express that I carry the sack first (earlier in time), and then the dog or the cat or both simultaneously, I can insert tenses to form Examples 17.10 through 17.12:
17.10) mi bevri le dakli .ije ba tu'e mi bevri le gerku
.ijacabo mi bevri le mlatu tu'u
I carry the sack. And [future] (I carry the dog.
And/or [present] I carry the cat.)
I carry the sack. And then I will carry the dog or I will carry the cat
or I will carry both at once.
17.11) mi bevri le dakli gi'ebake bevri le gerku gi'acabo bevri le mlatu
I carry the sack and [future] (carry the dog and/or [present] carry the cat).
I carry the sack and then will carry the dog or carry the cat or carry both at once.
17.12) mi bevri le dakli .ebake le gerku .acabo le mlatu
I carry the sack and [future] (the cat and/or [present] the dog).
I carry the sack, and then the cat or the dog or both at once.
Examples 17.10 through 17.12 are equivalent in meaning to each other, and correspond to the tenseless Examples 17.7 through 17.9 respectively.