How does languages with imperfect aspects typically convey distinctions between habitual, iterative, and progressive aspects?
In English, which does not mark its verbs for imperfect aspect, we have progressing "-ing," we have adverbial to convey habitual aspect ("always," "usually," "regulary") and even an auxiliary, "keep," that can convey iterative aspect.
In languages that do have imperfect aspect but no verb inflections or auxiliaries that mark distinct habitual, progressive, or iterative aspects, how are the concepts that answer to the latter three names conveyed? For example, is the use of adverbials to make these distinctions the most common strategy?