Circumstantial formWāw al-ḥālKey rationale
Affirmative imperfectNormally excludedResembles a single-word ḥāl; presents occurrence of a quality
Negative imperfectEither inclusion or omissionDenial of an occurrence or quality
Affirmative pastEither form may occurCompleted event, contextual evidence and qad
Negative past / past in meaningEither form may occurScope and duration of negation
These are rules for genuine circumstantial clauses, not every second sentence containing a verb. If an apparent counterexample occurs, first determine whether its construction is nominal, verbal, coordinated, or elliptical.