ExpressionFormPossible function
هَلْ أَنْهَيْتَ الْعَمَلَ؟InterrogativeActual inquiry or reproachful reminder
أَنْجِزِ الْعَمَلَImperativeCommand or helpful guidance
لَا تَتَأَخَّرْProhibitionProhibitive instruction or caring warning
The same morphological form can carry different functions in different contexts. This does not make all readings equally plausible in any one setting: actual discourse clues support a particular interpretation.
The analytical test is to identify the action or acknowledgment sought by the speaker, the addressee's position, and the question that preceding discourse makes relevant.