他鼓励的话语在困难时期带来了一丝希望。

His encouraging words provided a ___spark of hope during the difficult times.

老师的热情是点燃我对历史兴趣的火花。

The teacher's passion was the ___spark that ignited my interest in history.

一次单独的抗议可能引发一场全国性的变革运动。

A single protest can ___spark a nationwide movement for change.