英语听力：自然百科 神奇水世界 Water-4

 Let's look first. The fresh water that we depend on begins its life in the oceans. As the sun's rays beat down on the surface of the sea, they heat the water molecules² until some evaporate. It's the start of an extraordinary journey.

 

Here with water evaporates, it feels like it vanishes into thin air there. Although we barely notice it, water molecules are suspending around us all the time, just that we are only aware of it when they clump³ together as cloud.

 

At tiny one time, less than a thousandth of the world's water is up here in the atmosphere. It may not seem much, but this is what spreads water from the seas to the land.

 

The water molecule¹ doesn't hang around up here for very long. It fact, it spends less time up there in the atmosphere than in any other time of its journey. A mere⁴ nine days until a typical water molecule crashes the earth as rain.

 

For most of us, rain is perhaps the most familiar stage of the water cycle, but notoriously, the least reliable.

 

As the water falls as rain, it joins a bigger system, cascading⁵ and carving⁶ its way across the land surface as streams and rivers. Look at that, water, absolutely everywhere.

 

Rivers and rain are the parts of the water cycle that we depend on and yet they are only a tiny proportion of the world's fresh water, amazingly two percent of all fresh water on the planet, the rest of the earth’s fresh water is locked away, down there on the ground.

 

What a landing.

 

The vast majority of it is stored as ice. Most of the rest seeps⁷ deep into the earth where it's known as groundwater. Hidden away down here is the planet's second largest store of fresh water, but in the end, all water arrives back in the oceans and the cycle begins again.

1 molecule   

n.分子，克分子

参考例句：

• A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈̬f婘̬ 妈̬成的。
• This gives us the structural formula of the molecule.这种方式给出了分子的结构式。

2 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

3 clump   

n.树丛，草丛；vi.用沉重的脚步行走

参考例句：

• A stream meandered gently through a clump of trees.一条小溪从树丛中蜿蜒穿过。
• It was as if he had hacked with his thick boots at a clump of bluebells.仿佛他用自己的厚靴子无情地践踏了一丛野风信子。

4 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

5 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。

6 carving   

n.雕刻品，雕花

参考例句：

• All the furniture in the room had much carving.房间里所有的家具上都有许多雕刻。
• He acquired the craft of wood carving in his native town.他在老家学会了木雕手艺。

7 seeps   

n.（液体）渗( seep的名词复数 )；渗透；渗出；漏出v.（液体）渗( seep的第三人称单数 )；渗透；渗出；漏出

参考例句：

• Water seeps through sand. 水渗入沙中。 来自《现代汉英综合大词典》
• Water seeps out of the wall. 水从墙里沁出。 来自《现代汉英综合大词典》