英语听力：自然百科 走进西藏 tibet—5

The golden dome which is mounted right at the top of the prayer pole is the most sacred object of all. Or it will be once it's retrieved. The old Shamanic beliefs of Tibet ascribed magical powers to the landscape, but theres a far more tangible sourc

英语听力：自然百科 走进西藏 tibet—6

In this rugged and unforgiving terrain littered with fractured rock and ice-cold rivers, the slightest miscalculation may have fatal consequences. The snow leopard is the worlds highest living big cat. But theres another smaller predator that ranges

英语听力：自然百科 走进西藏 tibet—7

It's about 5,000 meters above sea level, way above the point at which altitude sickness starts to affect humans. At this height, most people are gasping for breath. But lack of oxgygen hasn't cramped this creature's style. Chiru, or Tibetan antelope

英语听力：自然百科 走进西藏 tibet—8

While the males fence, the females look on. Injured and weakened by the battle, the loser will be an easy target for the predators and scavengers that patrol the wilderness. Out here, there is little room for mistakes. With a clear view of the endles

英语听力：自然百科 走进西藏 tibet—9

The yak has even led the Tibetans to buried treasure. In summer,people can be seen scouring the grassland,bent over in deep concentration.This is the world's weirdest harvest.Tibetans first investigated this strange root-like organism,known locally a

英语听力：自然百科 走进西藏 tibet—10

Yartsa gunbu sells for big money in the top department stores of Lhasa and there is a growing market outside of Tibet. Although Tibet is modernizing fast, it retains a deeply spiritual culture. Even today, Tibetan valleys resound to distinctive and e

英语听力：自然百科 走进西藏 tibet—11

The possibility of escaping the cycle of life and death and the promise of enlightenment encourages people to perform activities that benefit all beings. This belief assigns as much importance to the environment and its creatures as it does to humans

英语听力：自然百科 走进西藏 tibet—12

Even today,black-necked cranes are treated with reverence and are welcomed by farmers as they land in the fields around the villages.Here, they perform their elaborate sky pointing rituals.After the dignified business of parading,they begin to forage

英语听力：自然百科 走进西藏 tibet—13

In such a frugal environment, the Pika's farming helps to kickstart the food chain. But the Pika itself is a very tasty morsel. Its presence has enabled an uneasy relationship to develop between the two plateau most opportunistic predators, the fox a

英语听力：自然百科 大迁徙 Great Migrations—1

They're born to move, to move or die, forging ahead against terrifying odds, navigating the first of millions of miles, spanning continents on fledgling wings, clattering ever onwards. Right now, our planet is on the march, on the wing, on the run, a

英语听力：自然百科 大迁徙 Great Migrations—2

What on earth could drive this headlong rush to slaughter? Only earth herself with her insistent clocks. This story begins in the Great Rift Valley, where the continent is tearing itself apart and being reborn. The plains in the shadow of the rift, t

英语听力：自然百科 大迁徙 Great Migrations—3

Apprentice killers wait for their taste of the chase. But they're about to learn that hell has no fury like a zebra protecting her foal. Older cheetahs know the value of patience. Soon, the herd will move on. Hungry eyes turn to one of the last-born

英语听力：自然百科 大迁徙 Great Migrations—4

Only the fit and the lucky will inherit the relay race of their lives. It is a race that is increasingly endangered like many of the world's great migrations. Climate change disrupts weather patterns and exploding human populations encroach on their

英语听力：自然百科 大迁徙 Great Migrations—5

It's a brutal, month-long migration, up to 5 miles, an ultra-marathon for a crab. The cruel sun makes its appearance, threatening them with dehydration. And they face a gauntlet of roads, crisscrossing the island. They stop only to nourish themselves

英语听力：自然百科 大迁徙 Great Migrations—6

Ravenous triggerfish seize the luckless, an unceremonious end to an epic quest. For the surviving males, the odyssey has just begun. The females will arrive within days, urged on by celestial forces demanding they reach the males and the sea in time.

英语听力：自然百科 大迁徙 Great Migrations—7

Then the brilliant masses take to the wing, heading to a place they've never been. Their only map, imprinted on their genes. A mysterious interplay of sun on eyes and antennae, an uncanny sense of magnetic north guides the way. It will take five mont

英语听力：自然百科 大迁徙 Great Migrations—8

For the delicate monarch, it may as well be a trip to the moon. And yet somehow they do it, their tiny bodies attuned to a seasonal sundial and resonating to the invisible signature of the earth's core--its magnetic field. Around the planet, animals,

英语听力：自然百科 大迁徙 Great Migrations—9

Females travel in family groups, sometimes leading their young on yearly wanderings of up to 20,000 miles. Each day, they gather to reaffirm their bonds. They seem to crave physical contact. Finally, the mothers disperse to feed in shifts. They leave

英语听力：自然百科 大迁徙 Great Migrations—10

A quarter of a million wildebeest will die in their yearly odyssey. In the sun burnt Serengeti, hunger keeps the wildebeests thundering northward, following the rain. A collective intelligence keeps the herd on track, neighbor leading neighbor, along

英语听力：自然百科 美国棒球运动

For generations, its been called Americas national pastime. Baseball has come to be seen as a defining part of the American culture, an enduring tie born from a diverse and sprawling young country. But the big business and athletic heroes that charac