In the last three decades the lakes have shrunk to less than half of their original size.

VOA: standard.2009.12.16

Efficient markets" is a theory about-- well it came in about three decades ago, maybe it's closer to four decades ago-- it's a theory that financial markets work very well and incorporate information very well.

有效市场是...,大约三十年前,甚至四十年前,有人提出了这一假说,他认为金融市场运行良好,而且信息披露全透明

耶鲁公开课 - 金融市场课程节选

The shortest term debt instrument in the United States is the Federal Funds Rate, which is an overnight rate--one day maturity-- and the longest issued by the Government is a thirty-year government bond, which will be repaid three decades in the future.

美国最短期的债券,是联邦基金利率,隔夜拆兑,一天到期,而时间最长的国债,是一种三十年期的政府债券,未来三十年才兑现

耶鲁公开课 - 金融市场课程节选

Dr.Charles Rabkin and other scientists from the National Cancer Institute looked at gastric cancer rates in the last three decades among a large group of Americans ranging in age from 25 to 84.

VOA: standard.2010.05.12