That is because the victims are vulnerable to exploitation, laws against this practice are not vigorously enforced and it is a hugely profitable trade.

VOA: standard.2009.08.21

And it was a practice that was not broadly used until somebody really studied systematically.

这项技术一直没有广泛应用,直到有人系统地研究它

耶鲁公开课 - 生物医学工程探索课程节选

And in terms of doing this for your homework, I actually want to mention that in the back page of your notes I attached a periodic table that does not have electron configurations on them. It's better to practice doing electron configurations when you cannot actually see the electron configurations.

关于你们的作业，是在你们讲义的后面的页,我附上了一张,没有给出电子构型的周期表,最好联系一下做出电子构型,当你们实际上看不到,电子构型的时候。

麻省理工公开课 - 化学原理课程节选

When someone invented the airplane, before you knew it every country had an airplane because there was a best practice, there was a best technology and it was not unique to any one country.

有人发明了飞机,不知不觉,每个国家都有飞机了,因为这些最佳的设计,这些最好的技术,并不是一个国家所独有的

耶鲁公开课 - 金融市场课程节选

Oftentimes, inventions that seem, in the abstract, to be good ideas may be impossible because something that you have to do to make it actually come into practice is too expensive and so it's not economic to produce the invention.

通常在理论上,创新固然不错,但却很难实现,因为把创意变成现实,花费会相当的昂贵,实现这样的创意非常不合算

耶鲁公开课 - 金融市场课程节选