The Arabian camel--not even a native , was domesticated in the deserts of Asia and brought to Northern Africa as a means of transport. In the past , Tuareg nomads used camels to move slaves, gold and

发表于:2019-01-02 / 阅读(112) / 评论(0)

浩瀚沙漠

Wild Africa - Deserts 浩瀚沙漠 - 15

Arabian camels and nomadic people are the most recent in a long line of Saharan pioneers. The history of this great region is told in ancient rock art, glimpses of a vanished world. Just a few thousan

发表于:2019-01-02 / 阅读(113) / 评论(0)

浩瀚沙漠

中国春节风俗习惯第1期:英国首相卡梅伦羊年新春贺辞

It's Chinese New Year and it can be a truly golden year for Britain and China. 现在是中国的农历新年，这也是英中两国关系的黄金一年。 Our economic relationship goes from strength to strength. 我们两国的经济联系不断增

发表于:2018-12-07 / 阅读(97) / 评论(0)

寻访外星人

中国春节风俗习惯第4期:中国羊年(3)

A hare came bounding along, and saw that the kind goat was shedding a tear. 一只野兔跳了回来，看到山羊在流眼泪。 Tell me good goat, why are you looking so sad? he asked. 告诉我，好山羊，你为什么看起来这么难过？他问

发表于:2018-12-07 / 阅读(84) / 评论(0)

寻访外星人

中国春节风俗习惯第3期:中国羊年(2)

One year, when the weather grew warm she began her annual journey, 一年，当天气变得温暖时，她开始一年一度的旅程， stepping slowly and steadily along the way, while her little kid skipped along beside her. 一路上缓慢而稳定

发表于:2018-12-07 / 阅读(82) / 评论(0)

寻访外星人

Alien Neighbors 寻访外星人 8

(NASA Administrator Dan) Golden accepts that the search for life on Mars is not over.

发表于:2018-12-07 / 阅读(76) / 评论(0)

寻访外星人

The Human Body: Life Story 生命物语-4

Everything that's alive and quite a few things that aren't, gives off heat. That's what you are looking at now. Every part of your body is burning up energy and creating heat as it goes about the busi

发表于:2018-12-07 / 阅读(86) / 评论(0)

生命物语

The Human Body: Life Story 生命物语-5

They are heart cells, and several million of them working at once is a heartbeat. In this case, it's your head that rules your heart as it's your brain that decides what rate your heart should be beat

发表于:2018-12-07 / 阅读(89) / 评论(0)

生命物语

Alien Neighbors 寻访外星人 2

From a planet.......let me get out of here....stay where you are.... Humanoid aliens have been good business in the 20th century. B moviemakers in particular have found a winning formula in showing se

发表于:2018-12-07 / 阅读(86) / 评论(0)

寻访外星人

The Human Body: Life Story 生命物语-6

...is actually the result of immeasurable activity inside our bodies. We are performing literally thousands of different tasks every second of every day. Simply being is part of an intricately complic

发表于:2018-12-07 / 阅读(81) / 评论(0)

生命物语

Genghis Khan 成吉思汗 - 15 (End)

But even this was not enough to satisfy the desire of Genghis Khan. He wanted something more, something his army could not give him, which is why in 1222, this man traveled towards Genghis Khan's cour

发表于:2018-12-07 / 阅读(107) / 评论(0)

成吉思汗

Supermassive Black Holes 超大质量黑洞 - 7

When it's feeding, a giant black hole creates a bright burning gas disk around it and then for some reason, it stops feeding, leaving a dark, deadly core lurking menacingly in the center of the galaxy

发表于:2018-12-07 / 阅读(307) / 评论(0)

超大质量黑洞

Alien Neighbors 寻访外星人 3

Launched in 1977, Voyager II explored the outer planets and their weird moons, moving ever deeper into space, into regions completely mysterious to us earthlings. On board is a gold-coated phonograph

发表于:2018-12-07 / 阅读(120) / 评论(0)

寻访外星人

Wild Europe - Genesis 肇始之初- 6

Parts of Pangaea were periodically flooded by shallow seas. But time and again this water evaporated, leaving layer upon layer of salt. Today these massive deposits lie buried deep beneath the Netherl

发表于:2018-12-07 / 阅读(102) / 评论(0)

欧洲自然写真

Supermassive Black Holes 超大质量黑洞 - 5

By measuring how fast these stars were moving, he could prove if there really was a black hole at the center of an active galaxy. I picked a galaxy nearby which is called NGC 1068, an active galaxy, w

发表于:2018-12-07 / 阅读(372) / 评论(0)

超大质量黑洞

Supermassive Black Holes 超大质量黑洞 - 4

This ferocious heart of brilliant hot gas is called a quasar. Scientists thought this whirling mass might be caused by a giant black hole sucking up gas and stars, literally feeding on the center of a

发表于:2018-12-07 / 阅读(300) / 评论(0)

超大质量黑洞

Supermassive Black Holes 超大质量黑洞 - 3

A supermassive black hole is quite simply gravity gone mad. An object of such concentrated matter its gravitational pull is insatiable. Nothing can escape it, not even light itself. Anything that gets

发表于:2018-12-07 / 阅读(362) / 评论(0)

超大质量黑洞

Supermassive Black Holes 超大质量黑洞 - 2

But we are just one in 125 billion galaxies of different shapes and sizes spinning through space. Yet scientists haven't been able to explain how a single one of these galaxies was created. Galaxy for

发表于:2018-12-07 / 阅读(355) / 评论(0)

超大质量黑洞

Supermassive Black Holes 超大质量黑洞 - 1

In March 2000, two astronomers made an extraordinary discovery, one that is set to overturn our understanding of how the universe formed. We're never going to see a time like this in astronomy again.

发表于:2018-12-07 / 阅读(386) / 评论(0)

超大质量黑洞

Supermassive Black Holes 超大质量黑洞 - 6

When the results came down from the telescope he saw something that was completely unexpected. The picture from the active galaxy where he hoped to find a black hole was unreadable. NGC 1068 was just

发表于:2018-12-07 / 阅读(330) / 评论(0)

超大质量黑洞

最新学习文章

热门学习文章

热门标签

英语听力 VOA标准英语 VOA 英语歌曲口语听力提高听力材料听力教程英语学习 NPR 英语口语 VOA慢速英语美国国家电台儿童英语 VOA英语小学英语 cnn VOA常速英语标准英语英文歌曲听电影学英语英语单词英文电影慢速英语 CRI 美联社新闻美国有线新闻加州分级澳洲新闻流行歌曲常速英语 ABC新闻快递疯狂英语英语读物听力棚车少年经济学人英语词汇商务英语 VOA双语新闻 BBC 中国电台大学英语 Treasures 加州语文 BBC英语英语听力网站 VOA英语教学词汇万花筒 SSS VOA英语听力 AP 新概念分级英语英语广播听力精选英语播客英文绘本 TED演讲赖世雄英语MP3 CCTV9英语新闻 lesson 英语新闻初中英语学英语英语语法历史上的今天英文广播剧英语游戏原版英语小说英语有声读物书虫英语牛津英语读物访谈录新闻一分钟考研英语英语每日在线听新闻 Us 新概念英语地道英语单词第二册自然百科高中英语 sports 实用英语 MP3听力辛沛沛 ESL英语第一册英语每日一句 unit 新东方 GRE 每日一词 BBC听力

学英语单词

a (absolute)

air refueling control team