当地时间21日中午，第57届美国总统就职典礼在首都华盛顿国会大厦西侧举行，奥巴马总统发表连任就职演讲，呼吁美国民众团结一致，抓住机遇。80多万观礼的嘉宾从全美各地蜂拥而至，他们都期盼着能够见证这一历史性的时刻，同时对奥巴马总统的第二任期也充满了期待。 Vice President Biden, Mr. Chief Justice, members of the United States Cong

OK, equation number one: Hard work plus bravery equals success. 好的，第一个等式：勤奋加勇敢等于成功。 However you define success, set your sights high. Be a hard grader on yourself. 无论你如何定义成功，都要抬高眼界。要对自己严厉一些。 When I st

It's probably as unlikely that you would nowadays become as rich and famous as Bill Gates, 今日你变得像比尔·盖茨一样，有钱又出名的机会， as it was unlikely in the 17th century that you would accede to the ranks of the Fren

(Video) Announcer: Threats, in the wake of Bin Laden's death, have spiked. （视频）播音员：在本拉登被击毙后，恐怖威胁数量激增。 Famine in Somalia. Announcer Three: Police pepper spray. 索马里出现饥荒。警察使用胡椒喷雾。 Vicious cartels. Causti

I call this ability collective learning. It's what makes us different. 我把这个叫做集体学习的能力。这使我们如此特殊。 We can see it at work in the earliest stages of human history. 我们可以看到在人类历史早期的阶段这种能力的运作。 We evolved as a s