英语听力：自然百科 黄石公园的夏天 Yellowstone—5

 As 6 months of snow and ice begins to melt, Yellowstone starts to come back to life. Cascading¹ snowmelt swells² the streams and rivers.

 

It's a hazard that the migrating herds³ must cross. Young are barely up to the task.

 

The Yellowstone river has increased its flow tenfold. 

 

In less than two weeks, the thaw has brought a remarkable change to the heart of Yellowstone

 

1 cascading   

流注( cascade的现在分词 )； 大量落下； 大量垂悬； 梯流

参考例句：

• First of all, cascading menus are to be avoided at all costs. 首先，无论如何都要避免使用级联菜单。 来自About Face 3交互设计精髓
• Her sounds began cascading gently. 他的声音开始缓缓地低落下来。

2 swells   

增强( swell的第三人称单数 )； 肿胀； （使）凸出； 充满（激情）

参考例句：

• The waters were heaving up in great swells. 河水正在急剧上升。
• A barrel swells in the middle. 水桶中部隆起。

3 herds   

兽群( herd的名词复数 )； 牧群； 人群； 群众

参考例句：

• Regularly at daybreak they drive their herds to the pasture. 每天天一亮他们就把牲畜赶到草场上去。
• There we saw herds of cows grazing on the pasture. 我们在那里看到一群群的牛在草地上吃草。