or is happening (or not) relative to speech time' and irrealis refers to 'the grammatical or lexical marking of an event time or situation that may have happened, or that may or may not happen in the future'. In Tamambo, the negative particle -te and aspectual lete can be used in conjunction with the 3SG irrealis a to express that a situation or action is not known to have happened. This is used because the negative markers cannot occur next to the future marker –mbo, however they can occur separately in the same construction evident in example [101] containing lete. In Tamambo, only the 3SG preverbal subject form has a irrealis, thus when -te is used with other preverbal subject pronouns, the time of event can be ambiguous, and phrases must be understood from context and other lexemes. For example, [98] illustrates the various interpretations one phrase may have. Negative verb tete The negative verb tete is a part of Tamambo's closed subset of intransitive verbs, meaning that it has grammatical limitations. For example, the verb tete can only be used in conjunction with the 3SG preverbal subject pronominal clitic. The negative verb tete can function with a valency of zero or one. Valency refers to the number of syntactic arguments a verb can have. Zero Valency The most common use of the verb tete is illustrated in example [59], where the verb has zero valency. The 3SG pronoun's of a (irrealis) and mo (realis) are used in conjunction with tete to respond to varying questions depending on whether the answer is certain or not. Example [60] illustrates the use of a and tete in a construction to answer a question where the answer is not certain. However, if the answer is certain than mo and tete are used highlighted in example [61]. Valency of one If tete functions with a valency of one, then the intransitive subject must precede the verb similar to a prototypical verb phrase. In this situation, 3SG marking can only represent both the singular and plural, highlighted in example [65]. Tete can also function with an 'existential meaning' illustrated in example [62], to express there was 'no one/no people'. Ambient serial verb constructions The negative verb tete can also be used following a verb in an ambient serial verb construction. In Tamambo, a serial verb construction is defined by Jauncey as 'a sequence of two