example ഓടുക (ōṭuka) – to run – and add the ending – യായിരുന്നു (yāyirunnu). To form the "used to do" imperfect, take off the ക (ka) from the end of the "uka" form and add മായിരുന്നു (māyirunnu) in its stead. To make a verb in the imperfect negative, add അല്ല് (all) after the ഉകയ (ukaya) part of the ending for the "was doing" imperfect. For example, ഓടുകയല്ലായിരുന്നു (ōṭukayallāyirunnu) (...was not running). To do the same for the "used to do" imperfect, take off the ഉമ (uma) from the ending and add അത്തില്ല (attilla) instead. For example, ഓടത്തില്ലായിരുന്നു (ōṭattillāyirunnu) (...didn't use to run) References Grammatical tenses