A group of students was told that a small democratic country had been invaded and had asked the U.S. for help. 在一项研究中，一群学生被告知某个民主小国在遭到侵略后向美国寻求援助。 And they had to make a decision. What should they do?
And then -- this is the key part -- that block is linked to the previous block 随后是关键的部分，该区块连接到前一个区块， and the previous block to create a chain of blocks. 以及更前面的区块，形成了一连串的区块。 And every one is time-stamp
Hi everybody. A few days ago, I unveiled a new national plan to confront the growing threat of a changing climate. Decades of carefully reviewed science tells us our planet is changing in ways that wi
Will these revolutions be whole like through the transitions to democracy or be overtaken by military or extremists of all kinds? 这些革命是否能引领国家向民主过渡,它们的胜利果实会不会被军方或者各种极端分子攫取？ We cannot tell. 我们无法预测。 Same
