波澜 (bō lán): billows; great waves (fig. of a story with great momentum)

Hearing this news, a wave of emotion surged in his heart, and he could not calm down for a long time.

Standing by the sea and looking at the waves on the distant water, she felt that her worries had become insignificant.

The plot of this novel is plain and lacks ups and downs; reading it makes one drowsy.

His speech caused a huge stir among the audience, and everyone stood up to applaud.

After years of effort, his life finally returned to calm, with no more big ups and downs.