It was the largest of the five major mass extinctions in earth's history, well before the dinosaur killer 66 million years ago. What's called the end Permian extinction 252 million years ago, wiped out 96% of aquatic species and 70% of species on lan

发表于:2018-12-24 / 阅读(51) / 评论(0) 分类 2014年Scientific American(二)月

Has Earths Gravitational Pull Been Changing? 地球的引力改变过吗? Don, why are you slouching? Dont you know its bad for you? 唐,为啥你无精打采?你不知道这对你不好? Did you know that about 200 tons of debris strike the

发表于:2018-12-28 / 阅读(54) / 评论(0) 分类 初学者听力文摘精选

Think back to your college days, the good old days when life was easy. Stay up all night partying or even studying? No problem. Eat pizza every night and plow through entire bags of potato chips at one sitting. Hey, no sweat. You were a lean, mean, a

发表于:2018-12-28 / 阅读(53) / 评论(0) 分类 初学者听力文摘精选

When the Pachyrhinosaurus bodies came to the bend in the river the momentum of the water push their carcasses to the outer edge of the bend. 当肿鼻角龙的尸体来到河流的转弯处,水流的动力将它们的尸体冲向河流转弯处外缘

发表于:2018-12-28 / 阅读(51) / 评论(0) 分类 侏罗纪搏击俱乐部

Why Is Gravity Good For Us? When astronauts return from long missions in space, their exit from the spacecraft is usually hidden from public view. This is because after several months in weightless conditions, things we usually take for granted, such

发表于:2018-12-31 / 阅读(75) / 评论(0) 分类 英语听力文摘 English Digest

Stay Thin By Sleeping More A study published Monday found that people who sleep less tend to be fat, and experts said it's time find if more sleep will fight obesity. We've put so much emphasis on diet and exercise that we've failed to recognize the

发表于:2019-01-02 / 阅读(50) / 评论(0) 分类 早读英语精华本

分集介绍:导数,斜率,速度与变化率 Derivatives.slope.velocity.rate.of.change

发表于:2019-01-05 / 阅读(321) / 评论(0) 分类 麻省理工学院公开课:单变量微积分

US Gun Control Advocates Disappointed by Vote At the White House Wednesday, with parents of the school shooting victims alongside, President Obama pledged to keep fighting for gun control. So all and all, this is a pretty shameful day for Washington.

发表于:2019-01-14 / 阅读(86) / 评论(0) 分类 VOA标准英语2013年(四月)

Mass Execution in Iran伊朗处决多名囚犯惹美国抨击 International observers and rights monitors have expressed grave concern over the reported mass execution earlier this month of some two dozen Sunni Iranians.There are few details availabl

发表于:2019-01-14 / 阅读(162) / 评论(0) 分类 VOA标准英语2016年(八月)

Fridays are the undistributed transb, awesome,I'm Carl L with cnn students news ten minutes commercial free advance.Start today with news from Jordan,the constitutional monarchy in the middle east,and its government is in raids.the isis terrorists gr

发表于:2019-01-19 / 阅读(83) / 评论(0) 分类 CNN美国有线新闻2015年2月

The X-ray image revealed how the black hole at the heart of the galaxy was firing unimaginable amounts of radiation into surrounding space and with extraordinary consequences. We could see what was going on at the centre and we could start to underst

发表于:2019-01-23 / 阅读(66) / 评论(0) 分类 探索与发现2013年

Was there any connection between the two? What Magorian discovered was completed unexpected. The relationship that we find was essentially that the bigger the galaxy, the bigger the black hole. That's in its broad terms. If you want to be a bit more

发表于:2019-01-23 / 阅读(59) / 评论(0) 分类 探索与发现2013年

The Vatican is prepared for a huge crowd Tuesday as Pope Francis hosts political leaders from 130 nations and representatives from a variety of religions for his installation Mass. Hundreds of thousands of people are expected to pack St. Peter's Squa

发表于:2019-01-25 / 阅读(55) / 评论(0) 分类 英语新闻

今天我们要学的词是 resume. Resume 动词,意思是恢复、重新开始。Classes have resumed at the Florida school where 17 people were killed in a mass shooting nearly two weeks ago. 两周前发生了一起大型枪击案导致17人丧生

发表于:2019-01-26 / 阅读(64) / 评论(0) 分类 英语单词荟萃

All right then! Imagine this weapon to be ten times stronger and the animal ten times more powerful, launch it at a speed of twenty miles per hour, multiply its mass times its velocity, and you get just the collision we need to cause the specified ca

发表于:2019-01-27 / 阅读(59) / 评论(0) 分类 《海底两万里》中英双语有声读物

发表于:2019-02-03 / 阅读(55) / 评论(0) 分类 考研英语

But, as powerful as Rome may have been, they couldn't change the rules of the universe, and neither of these calendars add up to anywhere close to the time it takes us to orbit the sun. After a few years, the seasons are out of whack with the months,

发表于:2019-02-14 / 阅读(83) / 评论(0) 分类 留美老师带你每日说英文

Let's say you're an eighteen-year-old male who runs every other day, logging 12 miles a week. Now fast-forward to your late 40s. Your eating habits are the same. To maintain your high school weight, how many miles a week would you need to run? Believ

发表于:2019-02-15 / 阅读(52) / 评论(0) 分类 英语时差8,16

That might lead to a different kind of dystopia (also with historical antecedents): one in which fast, functional transport is available only to those who can pay. 这可能会去往一个不同的非理想之地(也有历史先例):在那里,快

发表于:2019-02-17 / 阅读(53) / 评论(0) 分类 经济学人财经系列

Souvenirs for Kate and William's Royal Wedding Go On Sale 威廉王子和凯特的王室婚礼纪念品上市销售 Fans of the British Royal family around the world are making plans for April 29th 2011. That's the date that Prince William and Kate M

发表于:2019-02-21 / 阅读(54) / 评论(0) 分类 英语听力精选进阶版