enlighten|enlightened|enlightening

你能解释一下这个历史事件的背景吗？

Could you ___enlighten me about the background of this historical event?

他的讲座让我对气候变化有了更深刻的理解。

His lecture ___enlightened me about the complexities of climate change.

这次关于环保的讲座让我受益匪浅。

The lecture on environmental protection was truly ___enlightening.