老师发现很难维持课堂秩序。

The teacher found it hard to keep her class in ___order.

抗议活动陷入混乱后，警察被召来恢复秩序。

The police were called in to restore ___order after the protest turned chaotic.

市长承诺让这座城市的街道恢复秩序。

The mayor promised to bring ___order back to the city's streets.