It has a half-life of approximately three years at which time it stops decaying.

它生命的一半是三年,在三年的时候，它就停止衰亡。

麻省理工公开课 - 固态化学导论课程节选

Meanwhile, his youth was going away and now this imaginary student is now thirty-three years old never had time to marry or start a normal life.

与此同时，他的青春年华也已经逝去了,现在这位设想出来的同学已经33岁了,还没有结婚也没有开始正常人的生活。

耶鲁公开课 - 金融市场课程节选

Three years from now, that is after the next president has had time to enact this program and the program has had some time to begin taking effect will the number of illegal immigrants in the United States be higher, lower or about the same? Ken Judd.

年后，这期间，下届总统有可能制定相关法案,而该法案刚好也已经生效,美国境内的非法移民,是增多，减少还是持平？，肯·贾德你先来。

斯坦福公开课 - 经济学课程节选

By extending your time horizon to three years, or four years,or five years, it opens up a whole host of investment opportunities that aren't available to people that are playing this silly,short-term game.

只有通过将投资延长至三年,四年乃至五年,才会出现大量的获利机会,沉迷于愚蠢的短线操作,是无法得到这些机会的

耶鲁公开课 - 金融市场课程节选