是什么促使你那样说？

What ___prompted you to say that?

我不知道是什么促使他离开。

I don't know what ___prompted him to leave.

真正触动我内心并促使我写这封信的是最近发表的关于心爱物品的一系列文章。

What really touched my heart and ___prompted me to write this letter was the recently published series of articles about favourite possessions.