英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—4

But polar bear courtship is never straightforward. She likes to play hard-to-get. It's also a challenge for blizzardcam. She's testing his fitness, making sure he is a good catch. He skills on the slopes show room for improvement. And now, the female

英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—3

She blinks in the sunlight. She spent her confinement in semi-darkness. She checks that the coast is clear and then reveals her secrets. Time for a stretch. She's been cooped up with her cubs since she gave birth three months ago. They learn by examp

英语听力：自然百科 北极熊 冰上间谍 Spy_Bear—2

She pushes the camera down the slope, a tracking shot. As she films, there is no human presence of any kind. She even adjusts the camera to record her own exit. She must get her cub to the sea-ice before it breaks up and thaws, otherwise, they will b

英语听力：自然百科 大迁徙 Great Migrations—18

But there is desperation here for the crocs well. Eat well now, and they may survive leaner times for months even a year. It's easy to forget that death is as vital to the herd as life. The young emerge from this brutal baptism stronger and wiser. Ba

英语听力：自然百科 大迁徙 Great Migrations—17

The merciless yellow crazy ants take a terrible toll. But by sheer force of numbers and the inexorable will of their genes, they prevail. That is the fierce logic of migrations. But what is logical for the many can be madness for the few. At the Mara

英语听力：自然百科 大迁徙 Great Migrations—16

Finally, they can rest. For another five months, they will cling to this winter refuge, entering a sort of waking trance of energy conservation. Until the longer days of spring awaken them again to mate and pass along to the young--their migratory im

英语听力：自然百科 大迁徙 Great Migrations—15

Soon there may be violence as males joust to win female affections. But for now, everyone enjoys a touching reunion. The calf, out of his depth among these goliaths, returns to the mentoring eye of his mother. He may not leave her for another 10 year

英语听力：自然百科 大迁徙 Great Migrations—14

Many will drown in their frenzy to launch their eggs seaward. Most years, only a handful of their offspring survive. But sometimes, if wind and sea and luck are with them, a tidal wave of tiny crablings will return to these shores. There is no way to

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