When is the second clause circumstantial in «حَضَرَ الْمُدَرِّسُ وَالطُّلَّابُ سَاكِتُونَ»?

Supplementary Practice 2: Editing Rhetorical Expression, Context and Reasoning

• When it necessarily contradicts the teacher
• When both predicates are past verbs
• When it describes the state at the time of the teacher’s arrival
• When sākitūn is interpreted as an imperative