英语听力:探索发现

To discover why these twin planets followed separate paths and to explore what gave us our precious atmosphere, we have to travel back, back four and a half billion years to the birth of the solar system itself. The birth of the solar system created

发表于:2019-01-23 / 阅读(136) / 评论(0) 分类 探索与发现2014年

Our planet was spared this fate. The magnetic field generated by the Earths core blocked the solar wind, preventing it from blasting away the fragile air. But the Earths atmosphere was still very different from the one we breathe today. It contained

发表于:2019-01-23 / 阅读(141) / 评论(0) 分类 探索与发现2014年

We were left with this atmosphere made of molten rock and vaporous rock. It took millions of years for that atmosphere to fall out and to be replaced by an atmosphere made up of nitrogen and carbon dioxide and water vapour. These new gases came from

发表于:2019-01-23 / 阅读(160) / 评论(0) 分类 探索与发现2014年

Evidence of the first oxygen in the atmosphere. The gas was released by a humble microscopic living organism called cyanobacteria. Well it turns out cyanobacteria are the only things that can actually produce oxygen, so we know that at some point cya

发表于:2019-01-23 / 阅读(151) / 评论(0) 分类 探索与发现2014年

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

发表于:2019-01-23 / 阅读(188) / 评论(0) 分类 探索与发现2012年

One giant short-faced bear is more than a match for two lions. But in this bitter climate, lions cant afford to go without a meal for long. A mammoth calf in its first winter is a tempting sight. But mammoths are attentive mothers and they have the b

发表于:2019-01-23 / 阅读(178) / 评论(0) 分类 探索与发现2012年

As North America emerged from the grip of the last ice age, the door was opened to outsiders for the very first time. As these early immigrants pushed their way south, they found themselves in a land of an unimaginable opportunity, overflowing with g

发表于:2019-01-23 / 阅读(146) / 评论(0) 分类 探索与发现2012年

Denver International Airport is coming to life and about to receive the first arrivals today. By midnight, more than 1,500 aircrafts wouldve touched down here, delivering tens of thousands of people to this modern metropolis. But when did people firs

发表于:2019-01-23 / 阅读(150) / 评论(0) 分类 探索与发现2012年

A lone wolf weighs as much as four coyotes, but one on one it's still no match for a bison. Wolves, though, live and hunt in packs of up to 15 and when they launch a cooperative attack, they're devastating. First they get the bison on the run, then f

发表于:2019-01-23 / 阅读(186) / 评论(0) 分类 探索与发现2012年

Because these two bull mammoths both had broken tusks, they could have fought at closer quarters than they would do normally. Twisting and turning, they became locked in a deadly embrace. Even more bizarre, this twist of fate then caused a third fata

发表于:2019-01-23 / 阅读(256) / 评论(0) 分类 探索与发现2012年

Colombian mammoths had to feed almost round the clock to fuel their bulky bodies. But as the ice age ended, food was not the mammoths' biggest problem. A new and deadly predator began to infiltrate the plains, a match for any prey, even the mighty ma

发表于:2019-01-23 / 阅读(187) / 评论(0) 分类 探索与发现2012年

Bison calves are born in summer and can run within a few hours of their birth. They have no choice. The herd won't wait in its eternal quest to find new grazing. Smaller grazers are still found here, too. But they stay put instead of wandering the pl

发表于:2019-01-23 / 阅读(156) / 评论(0) 分类 探索与发现2012年

The Osage orange seeds were carried far across the plains, before being deposited, pre-packed in their fertilizer growbags, ready to take root. As the ice age waned, the milder climate and the mixed vegetation meant the plains were able to support a

发表于:2019-01-23 / 阅读(204) / 评论(0) 分类 探索与发现2012年

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

发表于:2019-01-23 / 阅读(220) / 评论(0) 分类 探索与发现2012年

The site was once a spring-fed pond, full of water. Mammoths were tempted in to drink. But when they tried to climb back out, the banks were steep and slippery. Just like the short-faced bear imprisoned underground, some became trapped. Scavengers wo

发表于:2019-01-23 / 阅读(196) / 评论(0) 分类 探索与发现2012年

Mud from the ancient riverbanks is good for building nests. lt also holds more evidence that will help us to reconstruct the ice age past. Every now and then,new clues surface, hinting at what else might lie beneath. ln this dried-up pond in South Da

发表于:2019-01-23 / 阅读(179) / 评论(0) 分类 探索与发现2012年

The death throes of the last great ice age left a signature that we can read today. These giant potholes were left behind by blocks of buried ice that melted, leaving hollows that later filled with water. For thousands of years since then, they've be

发表于:2019-01-23 / 阅读(174) / 评论(0) 分类 探索与发现2012年

Even the mastodon is buried here, a long dead relative of modern elephants. This was once a bear, but not like any bear in North America today. Claw marks gouged into the cave wall showed the bear was not killed direct by the fall. It made a desperat

发表于:2019-01-23 / 阅读(197) / 评论(0) 分类 探索与发现2012年

In a Colorado gully, hunters carried out a mammoth massacre, leaving behind the remains of at least 16 animals. The site recreated here contains a treasure trove of evidence relating to the mammoth's daily life. Again by comparing mammoth bones to el

发表于:2019-01-23 / 阅读(175) / 评论(0) 分类 探索与发现2012年

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

发表于:2019-01-23 / 阅读(194) / 评论(0) 分类 探索与发现2012年
学英语单词
adarces
afterlengths
antigas
antiseptic
aransas b.
arthroempyema
atomic scale
basepersons
be guilty of
binding board
branching program
brush grade
bullen-bullen
camshafteccentric
Cappoquin
captioning service
cephalitis
closed-circuit communications system
co-financing loans
core disassembly
current slicing
designed load line
disappointingly
dry-fire
dust separation
Egyek
Eichhornia crassipes
elected member
eminelntia collateralis
enstatite plagiaplite
feldspar in lump
fiber packing
flooie
foster sisters
frame wedge bolt
fusible metal film resistor
galaxiids
gift exchange
high energy particle spectrometer
high-major
Hungary waters
intermediate distribution frame (idf)
isobaric chart
isomerises
johl
kaalam
kluystron
kolmogorov complexity
least cost estimating
letter of indemnity
Leverett function
light guides
location for main engine
long-focus objective
Loriaux
Menguémé
milk-sop
motor structure mass
moved on
multilayer packaging
Murngin
muscular part of interventricular septum
music store
musteline
myohyoid line
Narégué
Nastenon
neocnemidocoptes laevis
neodecyllin
neutron-producer re-actor
nsila
numbering
palladium(ii) sufide
paralimbic
pelusios subniger
personalty
photo-thermo-elasticity
popular song contest
Primene
prissies
process shrinkage
puerto villamizar
record code
rontgenluminescene
rotating mechanisms
running trial
safety button
sarcotoxin
skunage
split cameras
steady state approximation
Sâmbôk
ten percent
TLW
Toloui
trente et quarante
unimpaired
univalent shift(person 1956)
whitmires
Wickenburgite
Zen garden
zigzag pattern