医生及时介入，防止了病情恶化。

The doctor ___intervenes in time to prevent the condition from worsening.

两个会议之间有一段短暂的休息时间。

A short break ___intervened between the two meetings.

老师在学生争吵时及时介入，防止了事态恶化。

The teacher ___intervened when the students were arguing to prevent the situation from worsening.