英语听力：探索发现 科学新发现：我们的大气层-23

But the friction and heat wears away at the space rock, the hot air actually melts the metal surface, and often the collision with the atmosphere can have a shattering effect, splitting the meteorites along fissures. This is an actual meteorite, and

英语听力：探索发现 科学新发现：我们的大气层-21

And above it the fragile air of the mesosphere is shielding us from a another deadly barrage from space. In east Texas, Jeff and Steve are searching for the remains of cosmic missiles that have been shattered by our atmosphere, fragments rarer than d

英语听力：探索发现 2012-11-28 美洲大平原 American Serengeti—14

13,000 years ago, the ice age cheetah was the pronghorn's greatest enemy. And pronghorn would have needed all their amazing speed. The American cheetah was larger than its African cousin. But it had the same Achilles' heel. A cheetah's high-performan

英语听力：探索发现 科学新发现：我们的大气层-17

You could use the balloons not just to go to the edge of the space as we do now,but go all the way over the line, and actually to use balloons or airships to go all the way into space,space travel without rocket.Officially, the atmosphere ends and sp

英语听力：探索发现 科学新发现：我们的大气层-15

But to fully forecast the floods, he needs a lot more atmospheric data. He believed robotic drone aircrafts developed for the military could continue to measure the air over the oceans, charting its temperature, wind and humidity. And the flight coul

英语听力：探索发现 科学新发现：我们的大气层-14

A single river can carry three times as much water as the entire Mississippi, they provide almost half the annual rain fall for parts of the American Pacific coast, but when they remain in one area for a day or more, they can produce violent flooding

英语听力：探索发现 2014-01-01 地平线：什么害死了我们的蜜蜂—18

Lin has recently become R* spokesperson in the neonicotinoid debate.-The big advantage of neonicotinoids is that you can plant the seed already treated. It means the farmer doesn't have to spray. If you've got to spray, it's very expensive. It's got

探索发现：History Channel:西恩宾回顾滑铁卢战役-24

好莱坞演员西恩宾（Sean Bin）回顾了滑铁卢这一历史上最具决定性之战役的故事。在影片中，他将引述那些当时参战的普通士兵的实际经历来讲述发生在1815年6月18日这一天的极具戏剧性的事件

探索发现：History Channel:西恩宾回顾滑铁卢战役-26

好莱坞演员西恩宾（Sean Bin）回顾了滑铁卢这一历史上最具决定性之战役的故事。在影片中，他将引述那些当时参战的普通士兵的实际经历来讲述发生在1815年6月18日这一天的极具戏剧性的事件

探索发现：History Channel:西恩宾回顾滑铁卢战役-25

好莱坞演员西恩宾（Sean Bin）回顾了滑铁卢这一历史上最具决定性之战役的故事。在影片中，他将引述那些当时参战的普通士兵的实际经历来讲述发生在1815年6月18日这一天的极具戏剧性的事件

英语听力：探索发现 2012-03-02 荒野求生 澳洲金伯利—1

I am Bear Grylls. Ive served with the British Special Forces. Ive climbed to the summit of Everest and crossed the frozen oceans of the Arctic. Now, Im in the Australias outback, a vast wilderness. Five million visitors come here every year to see th

英语听力：探索发现 2012-03-04 荒野求生 澳洲金伯利—2

Its suddenly just so hot. Its quite ncie and cool in the breeze of like 100-mile-an-hour slipstream. But suddenly you realize it is very, very hot. And its also just huge. Look at this. First thing, find a vantage point to see where you are. The Kimb

英语听力：探索发现 2012-09-30 长毛象王国 Mammoth—10

The fact that both horses and mammoths were here suggests these forests werent. It seems that, 14,000 years ago, Beringia was a huge expanse of open grassland. This unique habitat of cold, dry grasslands is known as mammoths steppe. But thats not how

英语听力：探索发现 2012-10-10 长毛象王国 Mammoth—14

Arctic ground squirrels hibernate like other small mammals, but with a unique twist. They can lower their body temperature right down to almost minus 3 degrees centigrade. But thanks to a biochemical super-cooling process, they dont actually freeze.

英语听力：探索发现 2012-10-14 长毛象王国 Mammoth—16

But back then, they had serious competition from the giant short-faced bear. The short-faced bears bone chemistry reveals it was a carnivore and up to a ton, probably the largest meat-eating mammal that ever walked the earth. On its long legs, it ran

英语听力：探索发现 2012-10-21 长毛象王国 Mammoth—19

They huddle and turn to face the threat, a giant short-faced bear. Faced by a wall of horns, the bear moves on to sniff out a less daunting meal. Occasional blizzards are another harsh reality of living in Beringia, but the drifting snow may at least

英语听力：探索发现 2012-10-05 长毛象王国 Mammoth—12

The male flicks the air with his tongue to test if the ewe will accept him. The next stage of courtship is not so subtle. He gives her a kick. At this highly-charged time of year, skirmishes can easily erupt between the rams, especially if they both

英语听力：探索发现 2012-11-11 美洲大平原 American Serengeti—7

The store of pollen paints a picture of the plains of 13,000 years ago, a picture that looks very different from the open prairie grassland of today. But why did this region look so different back then? The ice sheets to the north, although retreatin

英语听力：探索发现 2012-10-26 长毛象王国 Mammoth—21

The lions will have to try elsewhere. Could a bison be a more realistic prospect? The wind whips up again offering cover, and the hunters focus on a target on the fringes of the herd. Before long the carcass freezes and becomes difficult to eat. Aban

探索发现：History Channel:西恩宾回顾滑铁卢战役-20

I am David Forays. Reporting Iranqi troops advanced into the centre of Romati. The troops return to reclaim the city which was lost to Islamic State militants. Seven months ago supports men for Iraqis counter-terrorism service says there was fighting