Tense serves to relate the event time to the utterance time. (Ritter & Wiltschko, 2014, p. 1339) In Halkomelem, two of the non-personal second-position predicate particles mark tense, -əł ‘past’ and ceʔ ‘future’. (Suttles, 2003, p. 43) In Skwxwu7mesh, two important particles represent two tense morphemes: -t — past tense and ek’ — future tense. Both have variable syntax. While the past tense morpheme often seems to be optional, unless required to disambiguate, the future tense morpheme seems to be almost obligatory. (Jacobs, 2011, p. 87-88)
Jacobs, P. W. (2011). Control in Skwxwu7mesh. [Doctoral dissertation, The University of British Columbia].
Ritter, E., & Wiltschko, M. (2014) The composition of INFL: An exploration of tense, tenseless languages, and tenseless constructions. Nat Lang Linguist Theory, 32, 1331-1386. DOI 10.1007//s11049-014-9248-6
Suttles, W. (2004). Musqueum reference grammar. UBC Press. SFU Student Access.