There's some probability that it can get very, very close the nucleus, and that probability is actually substantial.

有一定的概率,它能非常非常接近原子核，这个概率是相当大的。

麻省理工公开课 - 化学原理课程节选

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