Tenses in Tulvan are divided in two groups: Strong Tenses and Weak Tenses. Again I would like to mention that the usage of the word "tense" in this context owes entirely to Tulvan classification. It is in fact a translation of the first scholars of Tulvan of the appropriate Tulvan term for them. The fact is that this groups tenses along with aspects and moods, which were actually historically related and developed thus. This is how Tenses are taught in Tulvan cathegories of strong and weak. The Strong Tenses are the ones which involve changing the root of the verb, these are: the Aorist, the Aorist participle, the Past, the Imperative and the Subjunctive. The Aorist is the normal form of the root and is translated as Simple Present or Gnomic Aorist, a kind of general present.
Lev kwam. I see.
Tulv kwam. I think.
Ëvud kwam. I know.
Thark kwam. I use.
Prum kwam. I speak.
The Aorist Participle is formed by the infixation of -y to the first vowel of the root. The only exceptions are the verbs that begin with rë- and ëv- prefixes. The meaning of these is that of a preceding condition or situation, almost an anterior tense, in the lines of the sentence "Do this and then do that". It is commonly translated as "having X, I do Y". So we have:
Leyv kwam. Having seen...
Tuylv kwam. Having thought...
Ëvuyd kwam. Having known...
Thayrk kwam. Having used...
Pruym kwam. Having spoken...
So for instance a sentence like tuylv kwam, ëv kem means "Having thought, I am", or even "Once I have thought, I am". Another example would be "Think and see!" this would be rendered into Tulvan as tuylv mem levi, using the imperative in the second verb.
The past is a little tricky. It has two forms depending on the verb. It uses the infixation of a- in the first thematic vowel in all verbs except the ones where that vowel is -a or -e, in which u- is used. So again we have:
Luev kwam. I saw.
Taulv kwam. I thought.
Ëvaud kwam. I knew.
Thuark kwam. I used.
Praum kwam. I spoke.
This is equivalent to the Aorist Past or the Simple Past. Then we have the imperative, this is an almost weak tense, because it employs the suffix -i, as in the title, so:
The imperative takes the suffix -in for the plural. So Prumi "speak!" referred to a singular "you", but Prumin "speak!/let's speak!" referred to a plural "you" or a plural first person. Finally we have the subjunctive very related to the imperative, it takes the form of the simple past plus the imperative suffix.
Luevi kwam. That I may see.
Taulvi kwam. That I may think.
Ëvaudi kwam. That I may I know.
Thuarki kwam. That I may I use.
Praumi kwam. That I may I speak.
This tense is rare, but it can be used as a lighter form of the imperative. It can also take the plural form -in.