Market experts say next year India is likely to try to import three million tons of rice tapping the world market for the first time in 21 years because of a drought.

VOA: standard.2009.12.17

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

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