In Maori grammar, the Perfect Progressive Theory refers to the expression of an action that started in the past, has been continuing in the present, and may continue into the future. This verb construction is used to convey the notion of an ongoing and unfinished action.

To form the Perfect Progressive in Maori, we start with the active particle “Kei,” followed by the causative particle “i,” and then the verb root. The verb root can be either a verbal noun or a verb stem with an “a” at the end. Finally, we add the suffix “-inga” to indicate progression.

For example, the sentence “Kei te whakapakari a Tama i te whare” means “Tama is strengthening the house” or “Tama has been strengthening the house.” In this example, “Kei te” shows the continuous aspect, “whakapakari” is the verb root meaning “to strengthen,” and “a Tama” indicates Tama as the person performing the action.

The Perfect Progressive Theory allows us to express actions in the past, present, and future tenses in Maori, highlighting their ongoing nature.