英语听力：2012-01-18 从南极到北极 From Pole To Pole—1

A hundred years ago, there are one and a half billion people on earth. Now, over six billion crowd our fragile planet. But even so, there are still places barely touched by humanity. This series will take you to the last wildernesses and show you the

数学英语 27 What is the Mode?

by Jason Marshall In recent articles, weve talked about two methods of calculating average values, the mean and the median, and weve talked about some everyday uses for them such as how to use median averaging to get better photos. But thats not all

英语听力：2012-01-20 从南极到北极 From Pole To Pole—2

The penguins stay when all other creatures have fled because each guards a treasurea single egg rested on the top of its feet and kept warm beneath the downy bulge of its stomach. There is no food and no water for them. And they will not see the sun

英语听力：2012-01-27 从南极到北极 From Pole To Pole—5

They are constantly on the move. New-born calves have to be up and running the day they are born. But the vast herds do not travel alone. Wolves. Packs of them, eight to ten strong, shadow the migration. And they are hungry. Its the newly born calves

英语听力：2012-01-22 从南极到北极 From Pole To Pole—3

But they are hungry and eager to reach their mother whos delayed feeding them on this special day. Now she lures them with the promise of milk, the only food the cubs have known since they were born, deaf and blind beneath the snow some two months ag

英语听力：2012-01-25 从南极到北极 From Pole To Pole—4

Day 10. And the mother has let her cubs a mile from the den. Its time to put them to the test. Theyve grown enormously in confidence, but they dont have their mothers sense of urgency. At last it seems that they are ready for their journey. And they

英语听力：2012-01-29 从南极到北极 From Pole To Pole—6

Midsummer on the tundra and the sun does not set. At these altitudes, the suns rays are glancing and not enough of their energy reaches the ground to enable trees to grow. Youll need to travel five hundred miles south from here before that is possibl

英语听力：2012-02-01 从南极到北极 From Pole To Pole—7

As we travel south, so the suns influence grows stronger. And at 50 degrees of latitude, a radical transformation begins. Summers here are long enough for broadleaf trees to replace conifers. Broadleaves are easier to eat and digest, so now animals c

英语听力：2012-02-05 从南极到北极 From Pole To Pole—9

The advance of the seasons brings constant change. As the suns influence diminishes in the north, so the deciduous forests of America begin to shut down, losing their leaves in preparation for the dark, cold months ahead. One season hands over to ano

英语听力：2012-02-08 从南极到北极 From Pole To Pole—10

The character of the forest changes as we descend, becoming ever darker and damper, favoring different kinds of animals and plants. Less than two percent of the sunlight reaches the floor. But even here there is extraordinary variety. In the Great Is

英语听力：2012-02-10 从南极到北极 From Pole To Pole—11

The female retires to consider her verdict. Its hard not to feel deflated when even your best isnt good enough. The sun influences the lives in the ocean just as it does on land. Its richest parts are those where waves and currents bring fertilizing

英语听力：2012-02-12 从南极到北极 From Pole To Pole—12

The strike of a great white shark lasts a mere second. Slowing it down forty times reveals the technique and immense strength of this massive predator. If surprise fails, there will be a chase. The shark is faster on a straight course, but it cant tu

英语听力：2012-02-15 从南极到北极 From Pole To Pole—13

The sun beating down on tropical waters powers the weather systems of the globe. Moisture evaporates from the warming ocean and rises to create great storms. The winds generated out at sea sweep inland across the continents. As they travel across the

英语听力：2012-02-03 从南极到北极 From Pole To Pole—8

Deer are frequent casulties of the harsh winter. And these leopards are not above scavenging from a corpse. African leopards could never survive here. But the Russian cats have thick fur to shied them from the cold. There are only 40 Amur leopards le

英语听力：2012-02-22 从南极到北极 From Pole To Pole—16

This is in Africa rarely seen, a lush water world. Some creatures are completely at home here. These are lechwe, antelope with hooves that splay widely enabling them to move at speed through the water. For others, the change is far less welcome. Babo

英语听力：2012-02-24 从南极到北极 From Pole To Pole—17

Their secret is teamwork. Impala are their favourite prey. They start to hunt and the pack splits up. An aerial viewpoint gives a new insight into their strategy. As the dogs approach their prey, they peel off to take up separate positions around the

英语听力：2012-02-26 从南极到北极 From Pole To Pole—18

The dogs know their prey must come out or drown. Now its a waiting game. The rest of the pack are calling. Theyve made a kill in the forest and this is an invitation to join in the meal. The impala is in luck. A pack this size kills once a day and ev

英语听力：2012-02-17 从南极到北极 From Pole To Pole—14

All across southern Africa, all animals are journeying for the same reason. Buffalo join the great track. Nowhere else on Earth are so many animals on the move for the same urgent purpose. They are all heading for the swamps of the Okavango, a vast i

英语听力：2012-02-19 从南极到北极 From Pole To Pole—15

At the peak of the dry season in the Kalahari, water arrives in the Okavango. It fell as rain a thousand miles away in the highlands of Angola and has taken nearly five months to reach here. The water drives out insects from the parched ground which

美国俚语:飞行模式 airplane mode

如果你要暂时逃离这个世界，与世隔绝，暂时不想和熟人接触，你可能会不接电话，不带手机，不上社交网站。通常是因为和恋人分手或者是工作不顺。 今天要介绍的俚语是airplane mode，用来形