Klingon does not express tenses (past, present, future). These ideas come across from context or other words in the sentence (such as wa'leS tomorrow). The language does, however, indicate aspect: whether an action is completed or not yet completed, and whether an action is a single event or a continuing one.
The absence of a Type 7 suffix usually means that the action is not completed and is not continuous (that is, it is not one of the things indicated by the Type 7 suffixes). Verbs with no Type 7 suffix are translated by the English simple present tense.
Dalegh you see him/her (legh see) qaja' I tell you (ja' tell)
When the context is appropriate, verbs without a Type 7 suffix may be translated by the English future tense (will), but the real feeling of the Klingon is closer to English sentences such as We fly tomorrow at dawn, where the present-tense verb refers to an event in the future.
This suffix indicates that an action is completed. It is often translated by the English present perfect (have done something)
Daleghpu' you have seen it (legh see)
vIneHpu' I wanted them (neH want)
qaja'pu' I told you (ja' tell)
-ta' accomplished, done
This suffix is similar to -pu', but it is used when an activity was deliberately undertaken, the implication being that someone set out to do something and in fact did it. English translations seldom reveal the distinction.
vISuqta' I have acquired it (Suq get, acquire)
luHoHta' they have killed him/her (HoH kill)
The second sentence above could not be used if the killing were the result of a general attack not intended to kill a specific person or if the killing were an accident. In such cases, -pu' would be used:
luHoHpu' they have killed him/her
The meaning of -ta' can also be indicated syntactically. That is, instead of using the suffix -ta', a special verbal construction can follow the verb which indicates the accomplished action. This special verb is rIn be finished, accomplished, and in this usage it always takes the suffix -taH continuous (see below) and the third-person pronominal prefix (0). The resulting construction, rIntaH, literally means it continues to be finished or it remains accomplished, It is used to indicate that the action denoted by the preceding verb is a fait accompli: it is done, and it cannot be undone.
luHoH rIntaH they have killed him/her (HoH kill)
vIje' rIntaH I have purchased it (je' purchase)
The English translations of rIntaH and -ta' are usually the same. The notion of absolute finality implied by rIntaH seldom comes across.
It should be noted that rIntaH is sometimes used for dramatic effect, even in cases when the action could be undone.
This suffix indicates that an action is ongoing.
nughoStaH it is approaching us (ghoS approach)
yIghoStaH steady on course!, maintain this course! (ghoS go, approach, proceed on a course)
Both of the above sentences suggest a continuing activity. The meaning of -taH can be seen clearly by comparing the following two commands:
yIjun execute an evasive maneuver!
yIjuntaH take evasive action!
In the first case, the maneuver is to be executed once only. In the second, a series of evasive maneuvers is to be executed ---the action is to be continuous.
-lI' in progress
This suffix is similar to -taH continuous in that it indicates that an activity is ongoing. Unlike -taH, however, -lI' implies that the activity has a known goal or a definite stopping point. In other words, it suggests that progress is being made toward that goal.
chollI' it is getting closer (chol get close, come near)
This word would be used for, i.e., a missile approaching a target, when it is known that the missile has been aimed at that target. If a missile is getting closer, but its intended destination is not known, choltaH (with -taH continuous) would be more appropriate.
vIlI'lI' I am transmitting (the data) (lI' transmit data to a place)
This word implies that data are in the process of being transmitted, but that there is a finite amount of data, so there will be a definite end to the transmission. The fact that the verb lI' and the suffix -lI' are identical in sound is purely coincidental, so far as can be determined.
The suffix -taH continuous can be used whether there is a know goal or not. -lI', on the other hand, can be used only when there is an implied goal. It is possible to consider -lI' a continuous counterpart of -ta', and -taH a continuous counterpart of -pu'.