leaven

一点背景音乐就能让最枯燥的家务活变得轻松些。

A little background music can ___leaven even the most tedious housework.

这位教授懂得用荒诞的假设性例子来活跃一堂枯燥的税法课。

The professor knew how to ___leaven a dense lecture on tax law with absurd hypothetical examples.

一个玩笑就能让原本沉闷的家庭遗产讨论变得不那么压抑。

A single joke can ___leaven an otherwise grim family discussion about inheritance.