undulate fold

例句：

1. 1. The waves gently undulated as the boat drifted along the shore.
   随着船在岸边慢慢行驶，波浪轻轻起伏。
2. 2. The river undulated through the valley, creating a picturesque landscape.
   河流在山谷中蜿蜒流淌，创造了一幅如画的风景。
3. 3.The plant's leaves undulate in the wind, adding to its graceful appearance.
   植物的叶子在风中起伏，增添了它的优雅外观。