英语听力：自然百科 大迁徙 Great Migrations—13

On Christmas Island, a different kind of home-coming preparation has begun. The males, though exhausted by their long pilgrimage, are readying snug burrows before the demanding females arrive in search of nursery-ready homes. Having dipped in the oce

英语听力：自然百科 大迁徙 Great Migrations—12

It takes four days for the larva to emerge. It gorges on its own egg case, before turning to tender milkweed. It must grow fat, build up its reserves for the long migration ahead. After two weeks of manic feasting, its body mass now 2,000 times what

英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—1

The islands of Svalbard in Arctic Norway. They might be remote, but they are under surveillance. Spy cameras are capturing the most intimate images ever taken of polar bears. They're revealing some remarkable behavior and discovering an animal of sur

英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—8

This new and ever-changing world requires a different spy-camera, iceberg-cam. It effortless steers between ice sheets and its turret rotates to follow the bears. The bear's lives are now governed by the state of the drifting ice and the movement of

英语听力：自然百科 智能电网（下）

Imagine you could find an explanation for anything in the universe, from the smallest events possible to the biggest. This is the dream which has captivated the most brilliant scientists since Einstein. Now, they think they may have found it. The the

英语听力：自然百科 也门首都：萨纳

Day breaks in Sanaa, Yemen as the call to prayer rouses the inhabitants of this ancient city as it has for hundreds of years. This capital city, nestled at an elevation of over 7,000 feet in the Yemeni highland, is one of the oldest continually inhab

英语听力：自然百科 天堂岛屿

Ever since man first began setting out for new lands by small boats heading over unknown horizons, he's been searching for among other things, paradise. And paradise in the Tuamotus, a small archipelago in the Pacific about 200 miles northeast of Tah

英语听力：自然百科 智能电网（上）

Its Friday afternoon at the village bakery in Hara Kebira. This tiny Jewish community is preparing for the Sabbath meal, bringing pots of soup to be heated in wood oven. Todays customers are Jewish, but the baker here is Muslim. In much of the world

英语听力：自然百科 飓风揭秘

An Atlantic hurricane often begins its life over the mountains in East Africa as an area of low pressure. It travels across the Sahara Desert, then moves out over warm ocean waters. Travelling with the trade winds and circles the globe just above and

英语听力：自然百科 伯利兹蓝洞

Why is this diver burrowing into the bottom of this mini lake? She is literally disappearing into the sand and gravel of the waters floor, only debris and the occasional bubbles from her breathing tank are visible. She is part of the project, largely

英语听力：自然百科 宇宙新领域 鲁特西亚真容曝光

Scientists are likening the new images from a large asteroid to discovery of a new world. Asteroid 21 Lutetia is located between Jupiter and Mars and the European Space Agency's probe Rosetta passed within about 2,000 miles of it, its onboard camera

英语听力：自然百科 神奇水世界 Water-1

Of all our planet's forces, perhaps none has greater power over us than water. For me, water is the most magical force on earth. The presence of water shapes, renews and nourishes our planet. Oh, my God ! You get all wet there! It's our planet's life

英语听力：自然百科 神奇水世界 Water-2

The center of the Sahara Desert in North Africa, one of the driest places on earth. I'm over six hours drive from civilization. Temperatures here regularly reach 100 degrees Fahrenheit, but there's less than half an inch of rainfall each year. Ah,the

英语听力：自然百科 神奇水世界 Water-3

Out there is a river valley that's been carved into the rock. It's been carved by running water, just flew down here smoothly off this rock bed and then cascaded down to the valley north there. Six thousand years ago, that was a big river. Satellite

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 molecules until some evaporate. It's the start of an extraordinary journey. Here with water

英语听力：自然百科 神奇水世界 Water-5

What that circulation means to us human is that water is a moving target. We constantly have to seek it out in this endless cycle and intercept it wherever and whenever we can. This quest depend on water has played a defining role in human history. T

英语听力：自然百科 神奇水世界 Water-6

It worked because the water of the river carried something special within it, an almost invisible treasure that was the secret of Egypts economic might. What made Egypt great is this stuff - silt. It's a rich supermineral silt, it's like an expresso,

英语听力：自然百科 神奇水世界 Water-7

So the rigid hierarchical structure of Egyptian society wasn't just dictated by the Pharaohs. It also emerged because the Egyptians had only one water source - the Nile. 5,000 years ago, it wasn't just the ancient Egyptians who noticed the value of r

英语听力：自然百科 神奇水世界 Water-8

society, that first brought civilization to the desert. Far from just scraping by in this harsh landscape, the Garamantes were flourishing. They grew crops, such as cereals and grapes. They kept horses and pigs. Clearly, they needed large amounts of

英语听力：自然百科 罕见的全黑帝企鹅

This all black feathered king penguin could be one in a zillion. The video was recorded on a sub-Antarctic island of South Georgia by National Geographic Traveler magazine contributing editor Andrew Evans on his bus to Antarctic expedition. While man